Small Dragons: Dragonflies, Anisoptera

Small Dragons: Dragonflies, Anisoptera

  On hot days with brilliant sunshine a dragonfly may point its abdomen upward to reduce the surface area exposed to the sun.

On hot days with brilliant sunshine a dragonfly may point its abdomen upward to reduce the surface area exposed to the sun.

 

This week we continue our adventures in the aquatic realm where we recently visited whirligig beetles and water striders. Now let’s meet some tiny dragons. Dragons are mythological beings common to many cultures. These fanciful and fearsome predators are often chimeras of several creatures with wings of a bat, head of a reptile, scales of a fish, feet of an eagle, or tail of a serpent. With enormous compound eyes, reticulate wings, long legs, and a snaky tail, dragon seems a fitting name for the insects we call dragonflies.

Dragonflies belong to a group of flying insects called the Anisoptera. The name Anisoptera comes from the Latin roots aniso- (meaning unequal) and –ptera (referring to wing). Anisoptera is a reference to the fact that the forewings of dragonflies are not nearly as wide as the hindwings. Dragonflies are an ancient clan. Those patrolling the skies 250 million years ago had wingspans of two and a half feet. Modern dragonflies are smaller but no less magnificent. They are active predators hunting and capturing prey while on the wing. Spiny legs held beneath the body in a basket-like arrangement trap victims. Small insects such as mosquitoes or crane flies are common snacks, but larger insects including bees, butterflies, and other dragonflies or damselflies may be captured. There are reports of large dragonflies catching hummingbirds.

On a chilly day in February it’s nice to think about a warm summer day when a dragonfly might choose a dragonfly ornament to perch upon amongst zinnias in my flowerbed. But dragonflies are fierce predators. Watch as a dragonfly devours a damsel in extreme distress – damselfly that is.

An empty shed skin attached to a stem is all that remains of a dragonfly’s life underwater.

An empty shed skin attached to a stem is all that remains of a dragonfly’s life underwater.

Male dragonflies often patrol specific territories along ponds or streams on the lookout for food, potential mates, or other males. Other males entering a territory are pursued and driven away. Females are wooed and mating pairs of dragonflies are often seen flying in tandem. The male sometimes guards his mate while she deposits eggs in the water or on aquatic vegetation. Eggs hatch into fascinating submariners called nymphs. These beautiful swimmers live in ponds or streams obtaining oxygen from the water through gills found inside their anus. Muscular contractions allow the nymph to pump water in and out of its rear-end to breath. How curious!

Dragonfly nymphs capture many kinds of insects such as the larvae of aquatic beetles, midges, and mosquitoes. Yes, dragonfly nymphs are important predators that help hold mosquitoes at bay. Crustaceans, worms, tadpoles, and even small fish are fair game for these stealthy hunters. Dragonfly nymphs sit and wait for a potential meal to come near. When in range, a remarkable, hinged mouthpart snaps forward like a bullfrog’s tongue to ensnare the victim. Nymphs usually move about by crawling slowly. However, when startled or under attack, they expel a blast of water from their rear ends and are propelled forward like a jet. After molting several times and completing development, a nymph will climb out of the water and attach itself to a plant or stone. The nymphal skin splits and the adult dragonfly emerges. Once the exoskeleton has hardened, the daring aerialist will take wing to hunt, mate, and entertain lucky humans on a warm summer day.

The insect on the left with gills on its tail is a damselfly nymph. The insect more centered is a dragonfly nymph. Watch mosquito larvae disappear into the maw of the dragonfly nymph, captured by the lightning strike of the nymph’s hook-bearing mouth-parts. Clips at normal speed have been slowed by 85% to observe prey captures.

Acknowledgements  

We thank Bill Lamp for providing the gorgeous dragonfly nymphs featured in this bug of the Week. Information was gleaned from “An Introduction to the Study of Insects” by D.J. Borer, D.M. De Long, and C.A. Triplehorn, “Beginner’s Guide to Dragonflies” by B. Nikula, J. Sones, D. Stokes and L. Stokes, and “Eco-Friendly Control of Mosquito Larvae by Brachytron pratense Nymph” by S.N. Chatterjee, A. Ghosh, and G. Chandra. 

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Palm Tree Diseases, Fungus & Pests

Learn How to Defend Your Florida Landscape Against Palm Tree Damage

If there’s something homeowners in Southwest Florida love, it’s sunny skies and sculpted landscapes. But as many of us have discovered, these landscape trees and plants can be vulnerable to a host of nasty insects, fungi, bacteria, and viruses.

Fear not!

By understanding the multiple types of diseases, fungus, and pests that can damage palm trees, homeowners can create a tree care plan to protect their Florida lawns.

Top Palm Tree Diseases, Pests & Deficiencies

From the statuesque Washingtonia palm tree to the elegant Canary Island Date, over 200 species of palm trees can thrive in the sunny climate we’re accustomed to in Florida.

The Lawn Care Services team at Catseye Pest Control cares about your landscape, and we would like to help you keep an eye on your landscape investment. Here’s a few of the conditions you should look for, and if the worst should happen, we’ll be here to help.

Rugose Spiraling Whitefly ​

A relative newcomer to the area, the invasive rugose spiraling whitefly is a lawn pest that first appeared in Dade County, Florida in 2009.

Since that time, the insect has become a serious concern. While this pest is most commonly found on palm trees, especially coconut palm trees, they are not exclusive to palms.

Susceptible plants include the black olive tree, gumbo-limbo trees, avocado trees, and mango trees, as well as many other species of ornamental plants and trees.

In the early stages of the infestation, spirals of eggs can be seen on the underside of the leaves. As the population grows it will drain nutrients from the host producing honeydew. This insect byproduct falls on the leaves and ground around the plant and fosters the growth of a black mold. The mold is commonly known as black sooty mold, which quickly becomes visually apparent.

Lethal Bronzing Disease

Lethal bronzing was first discovered in South Florida in 2006. While this disease is similar to the Lethal Yellowing bacteria, it is not identical.

Early stages are only detectable by a sudden death of any fruit or flowers currently on the tree. A pruned palm tree without the flower or fruit pods will not show this symptom.

As the disease advances, the lower limbs will suddenly brown and die. In the final stage, the “spike” or newest frond at the crown of the tree will collapse.

Unfortunately, these are the symptoms of multiple ornamental grasses and palm tree diseases. So, diagnosis should be performed by a trained professional and confirmed via laboratory testing.

Once the presence of the bacteria has been confirmed the tree must be removed immediately and destroyed before the infection can spread. The only means of management of this disease is through preventative antibacterial injection. There are 16 palm trees currently known to be affected, a few of which include: 

  • Bismarck Palm
  • Buccaneer Palm
  • Cabbage Palm
  • Canary Island Date Palm
  • Carpentaria Palm

Palm Weevil ​Damage

The largest weevil in North America, the palm weevil is native to Florida. The insect was once known to only affect damaged or dying trees. In recent years, however, it has​ ​become a danger to mature and healthy palm trees.

This palm tree bug was once primarily associated with the native Floridian cabbage palm. Now Bismarck palms, Canary Island date palms, and latania palms are all at risk. In addition, several other species of palm trees are susceptible to palm weevil damage, but only while immature or recently transplanted.

palm weevil damaged brown palm tree in a group of green palm trees

Early detection of activity is essential. The early stages of infestation will show as an odd drooping of the older fronds. Once the palm weevil progresses past this stage, death of the tree is almost certain.

In the final stage of palm weevil damage, the head of the palm tree will collapse. This is known as popping the head.

Nutrient Deficiencies ​in Soil

The Florida climate is ideal for palm tree species from around the world, unfortunately we have one disadvantage that can be overlooked and misunderstood by those unfamiliar with our environment.

Sand!

Sand might feel great under your feet, but it is terrible as a soil for non-native plant life.

Making matters worse, foundations for new homes have been using what is commonly referred to as fill dirt for the past few decades.

Not only is this soil terrible in terms of nutritional value for plants and trees, it is almost always high in alkalinity which can drain nutrients from trees and prevent them from receiving certain vital nutrients necessary for their continued health and growth.

Nutrient deficiencies can build up over time and lead to stunted leaves and fronds, discoloration and yellowing, palm tree trunk damage, narrow trunk caliber, and can even lead to infection caused by palm tree fungus.

Severe deficiencies can cause extreme deformation of the crown, crownshaft collapse, trunk and frond necrosis, in addition to possibly losing the palm tree.

Stressed trees lacking nutrition are more susceptible to insect infestations as well.

Whether you are moving into a new home or have a well-established landscape, proper fertilization and lawn irrigation for your palm trees is essential to the landscape’s continued success.

Tree Care Program in Southwest Florida

Without a plan in place, an otherwise healthy and bug-free tree can quickly collapse and die. Often, the beginning signs of nutrient-deficient palms can go unnoticed. By the time the warning signs become obvious it’s too late for the tree.

At Catseye Pest Control, we have a team of trained horticulture professionals with years of experience ready to properly care for your trees.

Using state-of-the-art materials combined with tried and true methods and specially formulated nutrients, Catseye offers lawncare services that can give your Southwest Florida landscape and trees the longevity and beauty desired.

For more information about palm tree fungus, how we can protect your landscape, and for a free inspection, contact us today.

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Protecting Your Home & Surrounding Property from Shrews

Learn About Shrew Habitats & How to Protect Your Home from an Infestation

Shrews are small mammals with cylindrical bodies, short limbs, and are amongst the hundreds of species of insectivores. This classification also includes hedgehogs and golden moles.

Their bodies are covered in grayish brown fur, except for their tail, which is hairless. Shrews bear a similar resemblance to mice, with the exception of their long, pointed snout.

closeup of a gray and brown greater shrew with long brown whiskers and a pinkish-colored snout and rounded ears standing on broken twigs

Like other animals, their appearance can vary depending on the species.

Shrews range in size depending on their species, but even at their largest, shrews are quite small. The Northern short-tailed shrew, for example, averages 4 inches in length, including the tail.

Shrew Behavior

Some shrews are nocturnal, while other species of shrews are active during the day. With this in mind, it is not unlikely to encounter one during the day.

Those living in colder climates could enter a state of lethargy and decreased physical activity known as torpor. This is not quite the same as hibernation.

Shrews do not enter a full state of hibernation. Torpor refers to the shrew’s ability to reduce their body temperature. This strategy allows them to conserve energy during the colder months.

Shrews can reproduce approximately three times each year, though they tend to mate during the warmer months. The average gestation period lasts roughly 21 days and can result in a litter of five to 10 young.

With the exception of mating, shrews are solitary animals that tend to live and forage on their own. The rodent can be extremely territorial and aggressive towards other shrews, animals, or even people.

If a shrew has made a home for themselves in your home, garden, or shed, you should leave control and removal to wildlife professionals.

Where Do Shrews Live?

With more than 300 species of shrews, the rodent is found throughout the world — including parts of Florida, New York, Connecticut and other states.

Shrews commonly found in the United States include the least shrew, southern short-tailed shrew, and the northern short-tailed shrew.

Shrews can live in a variety of environments, depending on the species. But the rodent mostly prefers environments that offer plenty of ground coverage, so they are protected against predators.

Some shrews live underground in abandoned burrows, while others live in gardens, tree cavities, and even manmade structures like homes, sheds, or businesses.

Can Shrews Get in Your House?

As we’ve learned, shrews are quite small. Gaps in foundations, spaces between windows or doors and siding, openings around pipes or conduits can all act as points of entry for shrews.

Relatively speaking, shrews are not destructive. Most of the damage caused by shrews happens outside. Digging tunnels throughout your property and eating any vegetation they can get their paws on.

However, they can cause damage while in your home or business. This includes contaminating food with urine or dark-colored and corkscrew-shaped droppings. They can also leave a putrid smell throughout the building as they mark their territory.

And much like other rodents, shrews carry and spread diseases like hantavirus and babesiosis. This makes proper handling and removal from Catseye Pest Control’s rodent and wildlife control technicians essential.

How to Keep Shrews Out Permanently

Trapping and removing unwanted animal intruders is just one part of the process.

Once the critter is removed from your home or business, it’s important to put a long-term wildlife exclusion solution in place to prevent them from getting back inside.

Cat-Guard Exclusion Systems is an environmentally friendly permanent wildlife barrier that protects homes, businesses, and other structures from rodents and wildlife getting inside.

Catseye technicians have the knowledge and experience to safely remove wildlife and effectively protect your home or business from future shrew infestations.

To learn more about Cat-Guard and for a free inspection, contact us today.

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Walkin’ on water: Water striders, Gerridae

  What forces and clever adaptations enable water striders to literally walk on water?

What forces and clever adaptations enable water striders to literally walk on water?

 

Last week we visited whirligig beetles and learned their secrets of living at the intersection of water and air. This week we return to the water to visit another member of the neuston, the interesting community of organisms that spend their lives on or near the surface of water. Gerrids go by a number of colorful common names including water striders, pond skaters, and Jesus bugs owing to their remarkable ability to walk just a few millimeters above the water’s surface. One fine autumn afternoon along a gentle stream in the Blue Ridge Mountains I happened upon a nice collection of water striders scooting across the surface of a small pool. Water striders are predatory members of the true bug clan that includes terrestrial predators such as wheel bugs and spined soldier bugs we met in previous episodes. These aquatic predators dine on small insects and other arthropods, either living or dead, whose fortunes deposit them on the water’s surface. Powerful jaws are used to penetrate the exoskeleton of a victim while needle-like stylets inject proteolytic enzymes to
liquefy internal structures of the prey. A pump in the head of the water strider sucks the nutrient-rich liquid into the predator’s digestive tract. Yum.

The majority of water striders are denizens of fresh water but a few live in brackish waters or truly saline waters of the ocean. As a group, they have evolved remarkably clever strategies for dealing with the uncertainties of aquatic life. Those utilizing large permanent water sources like lakes may lack wings entirely and forgo the ability to fly, putting their bodily resources into reproduction rather than mobility. Others found in temporary water sources often have winged individuals capable of escaping vanishing pools and colonizing new water-filled ones.

Small dimples in the water caused by cohesion of water molecules beneath each of six widely spread
legs distribute the strider’s weight, enabling it to stand and zoom across the surface without sinking.

Perhaps the most interesting aspect of water strider life is the unique ability to walk on the water’s surface. Here’s how they do it. The body of the water strider is covered with thousands upon thousands of fine hairs. The larger of these dense hairs covering the body repel water, keeping the strider from becoming water-logged and sinking when splashed or submerged by a tiny wave or pelted by raindrops in a downpour. The real magic comes by way of tiny microhairs found at the tips of the water striders legs. These can number more than a thousand hairs per square millimeter. By distributing its weight across six legs, each with water repellent hairs, the water strider takes advantage of the cohesive force of water molecules. Water molecules
simply stick together due to the attraction of one charged molecule to another. This cohesion causes the water to form small depressions beneath each leg as it bears the weight of the insect. To move forward, the water strider shifts minute amounts of weight to one of the middle legs and then pushes against the back wall of the depression thereby propelling itself forward. By alternating movements of the middle legs, steering with the hind legs, and carefully distributing its weight among all legs, the strider walks on water. One can only imagine what fun could be had if we had skates or shoes to exploit the cohesive force of water molecules.   

Acknowledgements

Two wonderful references “Aquatic InsectEcology” by J.V. Ward and “Insect Ecology” by P.W. Price, R.F. Denno, M.D.Eubanks, D.L. Finke, and I. Kaplan were used to prepare this episode.  

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Why four eyes? Whirligig beetles, Gyrinidae

  Viewed from the side you can see compound eyes of the whirligig beetle, one looking up, another looking down. Two on the right and two on the left make four. But the question is why?

Viewed from the side you can see compound eyes of the whirligig beetle, one looking up, another looking down. Two on the right and two on the left make four. But the question is why?

 

Having crossed the optical threshold of unaided vision many years ago, I find having four eyes – that is, wearing glasses – to be incredibly useful, especially when trying to observe the antics of very small creatures like insects. In this week’s episode we meet a fascinating beetle with four eyes. No, it doesn’t wear glasses, although that would be pretty funny, but it really does have four eyes. Beetles in the family Gyrinidae, commonly known as whirligig beetles, live the life aquatic at the interface between the world of air and sunlight and the world of swirling water. The name whirligig stems from their habit of swimming rapidly and changing direction frequently, often in circular patterns.  Some observers comment that these beetles seem to gyrate on the water’s surface.

Life at the interface of two worlds, one of air and the other of water, presents interesting challenges. One challenge of course is the very different way light passes through water compared to its passage through air, and how this difference affects vision. Many of us have had the interesting experience of observing aquatic creatures underwater at an aquarium or through the lens of a dive mask. You’ve seen that objects appear significantly larger underwater than when viewed in air. This phenomenon results from water refracting or bending light as it moves through water, making objects appear about one third larger than they actually are. Imagine the dilemma of a surface dwelling insect faced with the prospects of attempting to keep an eye open for predatory fish lurking below while simultaneously monitoring for hungry birds ready to pounce from above. Whirligig beetle have a unique solution to this visual dilemma. They have evolved two unique sets of eyes, one pair gazing upward above the water’s surface, one downward-looking pair immersed in the water below.  

Sneaking up on a raft of whirligigs plying the gentle currents of the Gunpowder River, the beetles appear orderly and intent on holding their place in the current. But with a quick wave of my hand, whirligigs quickly shift into the swirling, dizzying, pandemonium from which they gain their name and possibly avoid the jaws of predators.

Upward-looking eyes are covered with a maze of incredibly tiny features called nanostructures that enhance their ability to sense wavelengths of light in the visual range. Downward-facing eyes that peer into the relative gloom below the surface lack these nanostructures. Separate nerve centers in the beetle’s tiny brain receive visual information from both pairs of eyes, integrate this information, and use it to hunt prey, find mates, and avoid predators. It is difficult for a binocular animal like me to even imagine what all of this must look like. Amazing!

The rapid, swirling movements of whirligigs are thought to help confound visually hunting predators. Whirligigs have yet another defense against their aquatic enemies, this one a nasty tasting chemical called gyrinidal produced by glands in their abdomen. When offered whirligig beetles as a snack, largemouth bass rejected them. Crazy swirly swimming, noxious chemical defenses, and four compound eyes, these are the special powers needed for whirligig beetles to survive at the interface of air and water.

Acknowledgements

Bug of the Week enjoyed “Secret Weapons” by Thomas Eisner, Maria Eisner, and Melody Siegler, and “Under- and over-water halves of Gyrinidae beetle eyes harbor different corneal nanocoatings providing adaptation to the water and air environments” by Artem Blagodatski, Michail Kryuchkov, Anton Sergeev, Andrey A. Klimov, Maxim R. Shcherbakov, Gennadiy A. Enin and Vladimir L. Katanaev, that provided the fascinating information for this episode.

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Upside and downside of a warming world for the despoiler of hemlocks: Hemlock woolly adelgid, Adelges tsugae

  White bundles of fluffy wax are a sure sign of a woolly adelgid infestation on hemlocks.

White bundles of fluffy wax are a sure sign of a woolly adelgid infestation on hemlocks.

  Eastern hemlocks are beautiful native trees well suited for landscapes.

Eastern hemlocks are beautiful native trees well suited for landscapes.

Eastern hemlock is a wonderful tree native to North America, found in the wild stretching from the shores of the Chesapeake to the Blue Ridge Mountains and beyond. In neighborhoods it graces landscapes as an evergreen specimen or screen along property lines. More than six decades ago, the hemlock woolly adelgid, a dastardly sucking insect akin to an aphid, appeared near Richmond, Virginia. It likely entered this country on infested nursery stock from Japan. For many years this pest made its presence known mostly in home landscapes and parks, where it often disfigured and sometimes killed hemlocks. As it spread to the Appalachian Mountains, it killed thousands of eastern hemlocks in the Shenandoah, Blue Ridge, and Smokey mountains. A recent study estimated government and household expenditures to control hemlock woolly adelgid and lost property values when hemlocks died exceed $214 million annually in the United States. From Maine to Georgia this pest threatens eastern hemlock in the north and its rarer cousin, the Carolina hemlock, in the south.

The hemlock woolly adelgid has killed thousands of eastern hemlocks throughout natural and managed landscapes in eastern North America.

The hemlock woolly adelgid has killed thousands of eastern hemlocks throughout natural and managed landscapes in eastern North America.

This mini-monster spends most of the summer and early autumn hunkered down as an inconspicuous immature stage, called a nymph, on the bark of the hemlock near the base of needles. When the cold winds of winter blow in late October and November, the nymphs resume development and mature in mid-winter. Currently in my neighborhood this process is underway, with adelgids producing large amounts of white, woolly wax from which the woolly adelgid takes its name. The waxy cover provides protection for the adelgid and for eggs she will lay in the woolly sac in late winter. Between March and June, a second generation of adelgids will hatch out and mature, and then the cycle begins again with females producing the next batch of nymphs that will summer on hemlock twigs. Excepting the summer season of dormancy, developing nymphs and egg-laying females feed by inserting hypodermic-like mouthparts through the bark of twigs. The long, sucking mouthparts search along the tree’s vascular system and eventually find specialized tissues called parenchyma cells of the xylem rays. The mouthparts are inserted into parenchyma cells and the adelgid greedily robs the tree of its stored nutrients. Heavily infested trees decline in vigor, turn a sickly grayish – green color, lose their needles, and may die in five to ten years, if adelgids are not controlled.

What lies beneath the wax? Wax on reveals little, but wax off reveals wiggling legs and rows of wax-producing pores lining the underside of the bizarre looking immature adelgid.

We have painted a picture of the adelgid as a despicable pest very much accustomed to thriving in winter’s cold in many parts of the eastern United States. As the world warms, scientists fear the range of the adelgid will expand dramatically to many northern reaches in the United States and southern Canada. In these chilly lands, the adelgids’ hemlock hosts are currently protected by frigid winter temperatures lethal to the overwintering stages of the adelgid. As the world warms, this thermal refuge for hemlocks is in jeopardy. But there seems to be an upside related to the warming of our world with respect to the current geographic range of the hemlock woolly adelgid. Recently, scientists have discovered that in the southernmost lands invaded by the adelgid, the hemlock forests of Georgia, summer temperatures have become hot enough to significantly reduce the survival of the adelgid on imperiled hemlocks, particularly those at warmer low elevations. While a warmer world may open the door for the adelgid’s continued northward march, perhaps the same phenomenon will close the door to its persistence in the south. Only time will tell.

Acknowledgements

The following articles where consulted in preparation of this episode: “Economic impacts of non-native forest insects in the continental United States” by J. E. Aukema and colleagues, “Biology and Control of Hemlock Woolly Adelgid” by N.P. Havill, L. C. Vieira, and S. M. Salom, “Increases in summer temperatures decrease the survival of an invasive forest insect” by Angela M. Mech, Patrick C. Tobin, Robert O. Teskey, and J. Rusty Rhea, and Kamal J. K. Gandhi, and “Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict?” by Jeffrey S. Dukes, Jennifer Pontius, David Orwig, Jeffrey R. Garnas, Vikki L. Rodgers, Nicholas Brazee, Barry Cooke, Kathleen A. Theoharides, Erik E. Stange, Robin Harrington, Joan Ehrenfeld, Jessica Gurevitch, Manuel Lerdau, Kristina Stinson, Robert Wick, and Matthew Ayres.

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Scorpion glow, scorpion sting: Slenderbrown and other scorpions in Central America, Centruroides spp.

  Like psychedelic posters from the 60’s, rockin’ tropical scorpions glow beneath the beams of a blacklight.

Like psychedelic posters from the 60’s, rockin’ tropical scorpions glow beneath the beams of a blacklight.

 

One delightful adventure not to be missed is a nocturnal foray into the heart of a tropical rainforest. This escapade can produce memorable encounters with whip scorpions, large tarantulas, and giant katydids like those we met in previous episodes. During one such foray in Costa Rica, I was surprised to see a beautiful blue-green scorpion resting on the ground when a trail guide moved a fallen leaf and cast the beam of a blacklight near the path. Being a child of the 60’s, I was instinctively struck to understand what my blacklight posters shared with this stinging eight-legged rainforest predator. It turns out that blacklight posters contain compounds, phosphors, capable of capturing the high energy photons of UV light and releasing their energy in longer and less energetic forms of visible light, producing dazzling, glowing hues. Scorpion glow results when UV light is captured by two compounds, beta-carboline and 4-methyl-7-hydroxycoumarin, found in the scorpion’s exoskeleton. Once captured, UV’s energy is released in the form of eerie blue-green florescence.

A scorpion is revealed amongst leaves on the rainforest floor as it fluoresces bluish-green when illuminated by rays of a blacklight.

In a series of clever studies, Dr. Douglas Gaffin and his colleagues discovered that the scorpion’s entire body may act as a photoreceptor or universal “eye” used to detect different levels of light. Light in the UV range directed at scorpions produced bouts of rapid movement. These researchers suggested that the scorpion’s whole-body “eye” might help it move to places where light no longer illuminates its body, such as locations beneath vegetation where the searching eyes of larger predators were less likely to spot it. Whole-body photoreceptors might also be used by scorpions to detect the waning light levels of twilight, the signal to exit burrows and start their nocturnal hunt for prey.

Who’s that lurking in the corner of the bed frame? And is that another wedged in the crack above?

Who’s that lurking in the corner of the bed frame? And is that another wedged in the crack above?

On another tropical adventure in the rainforests of Belize I had the good fortune to encounter scorpions in a somewhat different context. After a long day of feeding mosquitoes and avoiding crocodiles with a group of students on a study abroad, the prospects of enjoying a little shut-eye in the bunkhouse was most appealing. Unfortunately, one student climbed into his lower bunk bed and was surprised to see a rather impressive scorpion beneath the mattress of the upper bed just a few inches above his head. In Belize, the solitude of bedtime is often punctuated by colorful and enthusiastic expletives describing the creatures found in cabins. The exciting Slenderbrown scorpion, like the one encountered by our student, is a regular visitor to cabins and outhouses at night, and goes by many names including the Slenderbrown, Brown Bark Scorpion, or Alacran azul. In the wild, I have seen it beneath loose bark and under logs. This scorpion is found in Central and South America, the Caribbean, and southern Florida.

Scary pinchers, or pedipalps, are used to capture prey.

Scary pinchers, or pedipalps, are used to capture prey.

If this sting gets you, you will be sending out an SOS to the world.

If this sting gets you, you will be sending out an SOS to the world.

Scorpions are not insects. They belong to another part of the arthropod clan called arachnids and are relatives of spiders and ticks. The scary pinchers on the front end of the scorpion are its pedipalps. They are used for grasping and dismembering insects and spiders that comprise most of the scorpion’s meals.

The business end of the scorpion is the sting, an enlarged segment at the end of the scorpion’s tail that contains a venom gland and a needle-like poker to deliver the poison. The sting is used to immobilize and kill prey and also as a means of defense against larger animals. When scurrying across a floor or ceiling, the scorpion’s sting is often curled up and over its back. Scorpions move surprisingly fast. The venom of the Slenderbrown scorpion carries a punch similar in pain to the sting of a honeybee or yellow jacket and is not generally life threatening. However, some relatives of the Slenderbrown scorpion, including those in the genus Tityus, are very dangerous and their venom can be fatal to humans. One courageous and somewhat impulsive student tested the potency of the Slenderbrown’s sting when she grabbed a scorpion lurking over her bunk and was stung. She summarily hurled said scorpion out the door of her cabin. Her assessment of the experience: “It only hurt a little and that thing was really annoying me”. You go girl!

Acknowledgements

Many thanks to Dr. Jeff Shultz for an enlightening discussion about scorpion glow. The fascinating article “Scorpion fluorescence and reaction to light” by Douglas D. Gaffin, Lloyd A. Bumm, Matthew S. Taylor, Nataliya V. Popokina, and Shivani Manna provided much background information for this episode. Thanks also to Matt Tabisz for wrangling the scorpion in this Bug of the Week.

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Wintry appearance of a strange moth: Fall cankerworm, Alsophila pometaria

  Wingless, flightless, non-feeding, winter-active, what a strange moth is this female fall cankerworm.

Wingless, flightless, non-feeding, winter-active, what a strange moth is this female fall cankerworm.

  Flight-capable male fall cankerworms are often seen on mild winter nights resting on trees or near porch lights.

Flight-capable male fall cankerworms are often seen on mild winter nights resting on trees or near porch lights.

Last year was spectacular for moths and butterflies. We visited many beautiful butterflies including brush-foots and swallowtails, and several marvelous moths such as silk moths and webworms. One of the more curious members of the moth clan, fall cankerworm, made its presence known on a blustery day last week. This enigmatic creature defies several “norms” found in the rest of the moth coterie. As you know, most moths are winged creatures that frequent the skies on summer nights as they search for mates and suitable plants on which to lay their eggs. However, female fall cankerworms are wingless. They have forgone their ability to fly. Is this some unfortunate twist of fate or the curse of a malevolent sylvan fairy? Perhaps, but many entomologists believe that wingless cankerworm moths have found a clever way to leave behind more offspring. By shifting precious bodily resources from equipment needed for flight, such as wings and muscles to flap them, and redirecting these resources to the production of eggs, female cankerworms may be able to bring more little caterpillars into the world and enhance their lineage’s odds for survival.

High in the treetops fall cankerworms deposit eggs on the bark of branches and twigs.

High in the treetops fall cankerworms deposit eggs on the bark of branches and twigs.

Regardless of the reason that underlies the mystery of the wingless moth, they are a wonder to see. Beginning in late autumn, adult fall cankerworms emerge from pupal cases in the soil. Females move from the soil and climb vertical structures such as trees and buildings. Shortly after sunset, on milder winter nights, female moths release a chemical signal called a sex pheromone that attracts male moths. Fall cankerworm males have functional wings and are good fliers. Each male tracks the pheromone to its source and the chilly couples mate. After this interlude, females climb high into the tree and place their eggs on the bark of small branches and twigs. Females do not live to see their offspring. Unlike other species of moths that have tubular mouthparts used to sip nectar, the female fall cankerworm lacks functional mouthparts. She cannot feed and shortly after depositing her eggs she dies.

Shredded leaves left behind by hungry caterpillars give these pests their common moniker, cankerworm.

Shredded leaves left behind by hungry caterpillars give these pests their common moniker, cankerworm.

The larvae of fall cankerworms hatch early in the spring soon after the buds of trees open and young leaves appear. Caterpillars of fall cankerworms and other members of their clan are also known as inchworms. They have multiple legs on their front and rear ends. By alternating their grasp between front and rear legs and bending their body upward into a loop, they move along twigs and leaves as if measuring the world an eighth of an inch at a time. The name cankerworm derives from the shredded, cankered mess caterpillars make as they consume foliage of trees. Their larvae reach phenomenal numbers in some locations and years, and may devastate many shade trees such as oaks, maples, elms, and lindens. We learned more about the ravages caused by this native pest in a previous episode of Bug of the Week. In addition to the fall cankerworm, other members of their clan such as spring cankerworm and linden looper, are active in the winter and have flightless females. A close relative of the fall cankerworm called the winter moth has recently appeared in cities and suburbs in New England, where it has become a perennial pest wreaking havoc on several species of shade trees in those areas.

On a bright winter day an adult fall cankerworm tries to ignore the annoying thumb of a bug geek. Can you guess why cankerworm caterpillars go by the name inchworms?

On a bright but chilly winter day visit a maple, elm, or oak and try to catch a glimpse of these strange ladies as they escape their earthly confines and slowly ascend trees in search of suitable repositories for their eggs. 

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A surprise visit from my ants: Citronella ants, Lasius sp.

  A cluster of female (larger ant) and male (smaller ant) smaller citronella ants seem ready to set forth to found new colonies on a warm afternoon in December.

A cluster of female (larger ant) and male (smaller ant) smaller citronella ants seem ready to set forth to found new colonies on a warm afternoon in December.

 

The appearance of winged citronella ants emerging from beneath my front sidewalk was a welcome surprise in this somewhat dismal season for observing insects and their kin outdoors in the DMV.  Swarms of winged, a.k.a. alate, ants are often seen emerging from the earth to mate and found new colonies in warmer months in temperate regions. However, ants in the genus Lasius have been observed emerging from the earth in Maryland as late as November, so maybe December 27 is not such an odd date to witness this remarkable event. While not an ant expert, these little rascals looked like the smaller yellow ant, Lasius claviger, to me.

What a holiday surprise! Watch as large winged
females, smaller winged males, and wingless yellow worker citronella ants emerge from the earth and swarm on my front sidewalk.

When disturbed, bright yellow worker ants release alarm pheromones to recruit nest-mates to assist in defending the colony.

When disturbed, bright yellow worker ants release alarm pheromones to recruit nest-mates to assist in defending the colony.

Lasius ants go by many colorful names including citronella ant, yellow ant, and lemon ant. The lemony scent we know as citronella owes to a compound found in many plants including lemon, lemon grass, and several species of eucalyptus. Special glands near the jaws of Lasius ants produce aromatic lemon scented citronellal. When threatened by an intruder, citronella ants send out an alarm by releasing citronellal. This pheromone brings nest mates running to assist in the defense of the colony. In addition to the well-known insect repellency of citronella, citronella ants have one more chemical trick up their sleeve, or should we say, in their rear end. Glands near the tip of the abdomen produce irritating formic acid. Formic acid contacting the eyes or face of an attacking predator serves as a powerful deterrent. This type of chemical warfare is an important strategy used by many species of ants.

Large yellow ants will sometimes swarm inside homes much to the dismay of unsuspecting homeowners.

Large yellow ants will sometimes swarm inside homes much to the dismay of unsuspecting homeowners.

In a previous episode we met large citronella ants that sometimes making a surprising appearance when their subterranean colony vents inside a home. Fortunately, Lasius ants are not wood destroyers like their cousins the carpenter ants. In addition to hunting soft-bodied prey, Lasius are herders. Yes, that’s right, they actually shepherd root feeding aphids, moving them from the roots of one plant to another to optimize the production of nutrient rich honeydew excreted by the aphids. As you may know, honeydew is an important and much sought-after food for many species of predatory and parasitic insects.

Citronella ants are relatively common in urban landscapes. I frequently encounter them while working in my flower beds and garden. You will too. Just take a moment to notice the pleasant fragrance of lemon as you turn the soil and then have a close look in the soil for these tiny and fascinating chemical warriors. 

Acknowledgements

The wonderful references “The Ants” by Bert Hölldobler and Ed Wilson, and “Secret Weapons” by Tom Eisner, Maria Eisner, and Melody Singer were used in preparation of this episode. Jeff and Linda shared the swarm of large yellow ants that emerged inside their home. Thanks also to Dr. Paula Shrewsbury for assistance with photography.

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Dashing through the snow: Snow scorpionflies, Boreus sp.

  Among frosty fronds, a scorpionfly gazes on a frozen landscape. Does she await her mate or ponder her next bite of moss?

Among frosty fronds, a scorpionfly gazes on a frozen landscape. Does she await her mate or ponder her next bite of moss?

 

Last week parts of the east coast were treated to their first real taste of wintry weather in the form of bone chilling temperatures, freezing rain, and snow. As we wind-down what has been a spectacular year for many of our six-legged friends, is it time to bid farewell to insects outdoors? Well, not exactly. You see, many tiny and not so tiny arthropods have adapted to a hibernal lifestyle and can be visited even on days when mammals are snoozing snugly in a cave or curled up in front of a fire sipping hot chocolate and reading a book. This week we visit one such character enjoying its day in the winter sun.  

Neither snow, nor ice, nor freezing temperatures can stop a female scorpionfly from scaling a miniature glacier to reach a scrumptious patch of moss. 

Carol Of The Bells by Audionautix is licensed under a
Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)
Artist: http://audionautix.com/

In a patch of moss near the banks of an icy stream, one of my colleagues discovered snow scorpionflies, one of the rarest insects we will meet in Bug of the Week. Snow scorpionflies are not scorpions, nor are they flies. They belong to a small order of insects known as Mecoptera. The “scorpion” moniker stems from the fact that some species of male scorpion flies have unusually large and upward curving genitalia that resemble the stinger of a scorpion. The “fly” part of the name comes from the fact that many species of Mecoptera have wings and can, well, fly. The tiny snow scorpionflies featured in this bug of the week do, in fact, lack functional wings, and cannot fly. Most species of snow scorpionflies are boreal and live in chilly places such as Alaska and Canada or occupy high elevations in mountains. They are active during the colder months of the year and can be seen with some regularity hopping about even on very frosty days. However, in Maryland snow scorpionflies can be found in the dead of winter on snow, ice, or on mosses and liverworts that serve as food for both adults and their larvae.

Chilly feet don’t cool the romance between winter-loving scorpionflies.

Chilly feet don’t cool the romance between winter-loving scorpionflies.

In one of the more curious mating rituals in the insect world, the male scorpionfly couples with the female, grasps her, and places her on his back for a nuptial ride. One has to wonder if this piggyback routine is just for fun or more likely a way to limit access to her by interloping suitors. If you hope to glimpse these fascinating creatures, dress warmly and bring along your magnifying glass. Snow scorpionflies are tiny insects, usually five or fewer millimeters in length. In a strange and still mysterious twist of evolution, snow scorpionflies are believed to be the ancient relatives of one of our more well known and itchy insect friends, the fleas.  

  Bug of the Week wishes all of you a Happy Holiday and a joyous New Year.

Bug of the Week wishes all of you a Happy Holiday and a joyous New Year.

 

 Acknowledgements

 Many thanks to Chris Taylor, Tom Pike, and Jeff Shultz for sharing his snow scorpionflies for this Bug of the Week. The wonderful reference “Scorpionflies, hangingflies, and other Mecoptera” by G. W. Byers was consulted in preparation of this episode.

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