Insects

The Secret Lives of Insects #8

July 20, 2021 By crm

Dragonflies: Jewels of the Insect World

By Judy Ferris, Master Naturalist & Guest Blogger

While brightly colored insects are noticed and admired, Dragonflies are the true jewels of the insect world. Their wings shimmer in a glittering array of patterns. Their huge eyes glow like gems and their bodies are colorfully painted. Add to this their extraordinary flight capabilities and clearly, this is no ordinary creature!

To scrutinize a Dragonfly is to peer into the past. Starting with the head, we note that unlike nearly all insects today, dragonflies have minimal antennae. Their vision, however, is acute. Massive compound eyes encompass nearly their entire head. Each eye has about 30,000 facets; receptors which bring visual information to the dragonfly’s brain. (Olberg 2009) Additional adaptations ensure that their color vision is probably better than ours! (Ryo Futahashi et. al 2014) How generous of Mother Nature to endow a 320 million-year old species with vision that modern insects, and even humans, would envy. Ever had trouble sneaking up on a dragonfly? Now you know why! 60,000 eye facets are monitoring your every move!

But nature’s gifts don’t stop at the dragonfly’s head. Its legs are one of the secrets of its success. A dragonfly’s thorax is specially modified to accommodate all of its legs up front. Pushing the legs forward in this way essentially makes the dragonfly into a flying basket for scooping up food. Spiny legs ensure that no insect escapes capture. The dragonfly then, snags prey on the wing, uses its mouth to rip off the wings so that the captive can’t escape, and feasts on its victim without ever having to land. What does a dragonfly eat? Glad you asked! Dragonflies are exclusively carnivores. Mosquitoes and midges are dietary staples, but anything that can be captured in the air, including Deer Flies, Butterflies, and other dragonflies, is fair game.

Watch this 1-minute video of a dragonfly eating a mosquito. Note the positioning of the dragonfly‘s legs; basket-like and perfect for capturing prey.

Folks who study insects consider dragonflies to be ‘primitive winged’ because unlike modern insects, dragonflies are unable to fold their wings when not in use. Their wings are forever held out at a 90-degree angle to the body. Ah, but this is not just any old set of wings! The front and rear wings of a dragonfly are able to act independently from one another. This unique wing configuration is the reason that dragonflies are Masters Of The Air. They can hover like helicopters, turn on a dime, and dart swiftly from a standing start. Today’s modern insects flap their wings at a speed of about 1000 flaps per minute. Dragonflies? Hardly raise a sweat; flapping only 30 flaps per minute. These amazing flight capabilities are yet another source of envy for today’s insects! Perhaps primitive’ is not so bad after all!

Click below to watch a beautiful slow-motion video by BBC of a dragonfly in flight. 1 ½ minutes in length.

Dragonflies are superb hunters. But mighty though they may be, after hundreds of millions of years, they still remain tied to the water. Dragonfly nymphs (larvae) develop in water for months and sometimes years before becoming adults. You might expect dragonfly babies to be elegant and artistic. But NO! Dragonfly nymphs are the stuff of horror movies! Imagine a small (1/4 to 1 ½ inches long), crayfish-like creature with a large head containing a lethal lower lip (labium). The nymph’s lower lip is hinged, rather like bending your arm and tucking it in to your chest. The lip can shoot out, snag prey, and drag it back into the mouth so fast that if you blink, you’ll miss it!

To check this out for yourself, watch this excellent 3-minute video from PBS ‘Curiosity Stream’ on dragonfly adults and nymphs.

Dragonfly nymphs eat the larvae of mosquitoes and mayflies, as well as tadpoles, and even small minnows. The nymphs themselves, of course, are a favorite food of frogs, fish, and snakes. It is estimated that the mortality rate of dragonfly nymphs may be as high as 99%! (Arnett 2000). Thus, no matter how lethal your lip is, if you are a nymph, it pays to have a good escape strategy. Mother Nature had to work hard on this one but as always, came up with a novel solution.

1. A dragonfly nymph has gills in its rectum. Thus, the nymph continually takes water in and out through its anus to breathe. [No. I am not making this up!]
2. If threatened, the nymph uses the powerful muscles of its rectum to blast water out of the anus.
3. Whoosh! Powered by the blast, the nymph is jet-propelled at high speed away from danger, leaving only a camouflaging plume of disturbed debris in its wake!

Dragonflies were perfect when they were created 320 million years ago and remain so to this day. In both the larval and adult stage they are master predators; helping keep mosquitoes, flies, and other pests in check. They also serve as an important food source for other creatures. Dragonflies are good indicators of a healthy environment and clean water. How wondrous that these jewel-like super-predators, capable of astonishing aerobatic and aquatic feats, still share our world and bedazzle us today.

It ‘s easy to be smitten by these astonishing insects! If you would like to learn how to attract dragonflies to your yard, check out the link below.

Tree hugger; “How to Create a Dragonfly Garden”

https://www.treehugger.com/how-create-dragonfly-garden-4863982

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The Secret Lives of Insects #6

June 17, 2021 By crm

Ground Beetles: Midnight Marauders

By Judy Ferris, ACLT Guest Blogger

Who would imagine that a beetle with a face like this would be a gardener’s best friend? Your first instinct upon seeing this critter may be to stomp it before it hurts someone. But wait a minute!

Ladybugs, move over! It’s time we discovered the nocturnal guardians of our gardens. Night after night, unnoticed and unloved, humble Ground Beetles toil to rid our gardens of pests. They are, in fact, some of the most beneficial insects in our gardens. Since Ground Beetles are nocturnal, however, we seldom notice them. By day they hide in grasses, or beneath rocks, logs, or mulch in order to stay cool and moist. As the sun sets in the evening, however, adult and larval Ground Beetles begin to hunt. They churn below the ground, skitter atop the soil, climb plants, and even ascend trees as they forage. What’s on the menu? It’s an all-you-can-eat buffet at the Insect Smorgasbord! Ground Beetles are prodigious consumers of a wide variety of insect pests that we would happily remove from our gardens; mites, snails, slugs, caterpillars, earwigs, cutworms, vine borers, aphids, and many other insects.

Ground Beetles are members of the Carabid family. With over 2000 Carabid species in North America alone, Ground Beetles are a common insect. They range in size from 1/8 to 1 1/2 inches long. If we examine this beetle closely, we can see that it is configured to be the perfect nocturnal predator. Ground Beetles rarely fly. Instead, they use their long, agile legs to hunt and pursue prey in the darkness. Most Ground Beetles are dark and shiny. They have large eyes as befits a night hunter. Those take-no-prisoners jaws are perfect for processing all kinds of prey; from slimy slugs, to gummy-bear cutworms, to crispy-critter ants. Some Ground Beetle jaws are even designed to puncture the shells of snails.

To watch those intimidating jaws in action, check out the video below Ground Beetle vs Corn Ear Worm. Warning! The video is best not viewed immediately before or after a meal!

An adult Ground beetle can eat its own body weight in prey insects nightly. Beetle larvae are equally voracious. A single beetle larva can eat more than 50 caterpillars during the course of its development.

As a family, Ground Beetles are the master chemists of the insect world. Thanks to chemistry, many Ground Beetle species can emit a lingering noxious smell from their rear ends to discourage predators. One branch of the Carabid family, Bombardier Beetles, has elevated this talent to an art form.

Behold the Bombardier Beetle! When threatened, this elegant little beetle can aim and shoot a hot, chemical cocktail from its butt to a distance of several times its body length. The chemical blast is accompanied by smoke as well as an audible pop as the chemicals detonate. How does the beetle do this? According to researchers at Penn State University, ground beetles have a unique gland system which allows them to store toxic chemicals such as formic acid, concentrated hydrogen peroxide, and phenolics in the tip of their abdomen. When needed, the chemicals are squeezed out of the glands and moved into firing position near the anus. There, the chemicals react with special enzymes to ‘fire’ (oxidize) the chemicals; releasing heat and gaseous oxygen that shoots the boiling hot (212 degrees!) material out of the Bombardier’s butt (Marshall 2006).

For a fascinating 4-minute video from the BBC on chemical warfare in the insect world, click on the link below. You’ll see Bombardier Beetles in action at the end of the video. Impressive!

In case you are wondering… Yes, a blast from the Bombardier Beetle can burn your fingers and stain your hands. Thus, if you are lucky enough to find a Bombardier Beetle, it’s best not to handle it. Personally, however, I’m delighted to know that a squadron of Ground Beetle caretakers patrols my gardens nightly, apprehending and puncturing pests! When I do happen upon them by day, Ground Beetles are not threatening, but are instead, welcome residents. May they live long and have many babies!

To attract beneficial ground beetles to your garden, create a simple beetle refuge as described below by Landscape Designer Darcy Larum.

“Build a small raised garden bed at least 2 feet wide and 4 feet long. Plant native perennials and grasses in this bed and give it a good layer of mulch. Add some large rocks or logs for décor and ground beetle hideouts. Let debris build up enough to encourage ground beetle eggs, but not too much to snuff out plants. Do not mow, till, or spray pesticides in this area.”

Additional information on Beetle Banks: https://savvygardening.com/build-a-beetle-bank-or-bump/

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The Secret Lives of Insects #5

June 1, 2021 By crm

The Scarab Beetles Are Coming! Exotic Jewels of the Orient or Upside Down Racers?

By Judy Ferris, ACLT Guest Blogger

Scarab. The word conjures up images of ancient Egypt, where a pantheon of animal-gods presides over both the weak and the mighty. Incense swirls amidst the bejeweled robes of powerful pharaohs. Scarab Beetles (specifically Dung Beetles) rose to prominence in this mystical world about 1500 BC. It all started when it was observed that dung beetles consistently rolled balls of ox dung from east to west. Just like the daily movement of the sun! Thus, the lowly Scarab Beetle became associated with the Gods. Specifically Kephri, god of the morning sun, who was thought to roll the sun into the eastern sky each morning and bury it in the west each evening. In fact, when hard at work, dung beetles really DO face east. It is a means of staying oriented as the beetle deftly rolls huge dung balls with its hind legs while facing backwards.

Click below for a 3-minute not-to-be-missed Dung Beetle Video. Everything you always wanted to know about dung rolling but were afraid to ask.

In ancient Egypt, the humble, dung-rolling Scarab Beetle eventually became a symbol of immortality, resurrection, and transformation. Scarab amulets, scarab stone carvings, and scarab images proliferated throughout the kingdom. Now THAT’S something an insect can brag about! (Sorry, no Scarab T-shirts.)

Unfortunately, here in Maryland, our most familiar representatives of the Scarab family are not the sacred dung-rollers of yore. Our most commonly observed Scarabs are June Bugs, Japanese Beetles, and jewel-like Green June Beetles. Today, we’ll focus on those gorgeous green and gold beetles with the monster appetites; Green June Beetles (Cotinus nitida).

When it comes to Green June Beetles, the larvae (especially the 3 ^rd larval stage), are more intriguing than the adults. These chubby grub babies are not going to win any beauty contests, but you do have to admire their unique adaptations. Green June Beetle larvae spend the majority of their grub-hood in burrows underground, feeding on roots and organic material. They sometimes emerge from their burrows at night to feed on nearby plants but return to their burrows as the sun rises. Heavy rains, however, can sometimes flood the grubs out of their burrows and set them to wandering in search of a new home.

Perhaps you are wondering “What are those little brown things sticking out near the head?” They look like miniature antennae, but in fact they are vestigial legs. The legs are too small to drag the heavy grub. Thus, this larva moves from place to place upside down! Yes, this is another of those extraordinary work-arounds derived by Mother Nature. Clearly, when legs and heads were handed out millions of years ago, Green June Beetle larvae were not paying attention. That tiny pin-head surely must have been earmarked for some other creature. And those pathetic, skyward-pointing brown legs? Never intended to transport a plump grub the size of a whole peanut. But don’t worry! Mother Nature to the rescue! She created a back-up system for the Green June Beetle grub. The grub’s back is upholstered with stiff bristles for traction and tough, road-gripping skin. Thus equipped, the grub is able to zoom on its back at speeds of 2 1/2 feet per minute! Before you start poo-pooing this velocity achievement, just try this method of locomotion yourself. Upside down, legs and arms in the air. OK, I admit it. Not being a goddess of abdominal muscles myself, I was dismayed to discover that, in a race, the speedy’ Green June Beetle grub would have passed me in 5-6 minutes and would be doing a victory dance at the finish line while I was still squirming at the start line!

Green June Beetles finally emerge from the ground as adults in June and July. Just imagine! The adult phase of life must be a heady whirlwind of discovery. After nearly a year of tunneling underground, emerging adults experience a totally new world of sunshine, rain, wind, flight, other Green June Beetles, sex, and an endless buffet of greenery and fruit. Their moment to frolic in the sun, however, is fleeting. In a few short weeks, eggs are laid for the next generation and the adults will die.

Though we may no longer worship Scarab Beetles, even the lowliest insects have their virtues. Like nature’s janitors, Scarabs convert what we consider to be waste material (dung, rotting plant material) into protein and fats. Large beetles such as scarabs are increasingly scarce world-wide, yet are an important source of fat and protein for birds. Scarab grubs are vital links in the food chain; high quality nutrition in a plump, defenseless package! A fat grub is a welcome treat for opossums, raccoons, skunks, birds, snakes, and even other insects. Next time you are buzzed by a low-flying Green June Beetle, take time to ponder its revered dung-rolling cousins, its high food value to wildlife, and of course, its unique upside down grub locomotion. Mother Nature definitely has a sense of humor!

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The Secret Lives of Insects #4

May 20, 2021 By crm

Silver-Spotted Skippers: Leaf Tents & Projectile Poop!

By Judy Ferris, ACLT Guest Blogger

Skippers may not be as colorful as their butterfly cousins, but they make up for it in feistiness. Walk into a male Skipper’s territory and he immediately pops up to inspect you. Zipping rapidly from perch to perch, he seems more closely related to a jet fighter than a fluttering butterfly.

Skippers branched off early, during the time of dinosaurs, from the line of butterfly evolution. They tend to be drab in color and have large heads and stocky bodies. The name Skipper’ comes from their rapid, erratic flight style. Male Skippers often rest on platforms such as flowers to scan for passing females. Periodically, they zoom forth to patrol their territory and drive away usurping males or, perhaps, gardeners.

The most common Skipper in much of the U.S. is the Silver-spotted Skipper. It is easily identified by its large size (wing span about 2 inches) and the large white spot on its wings. The success and abundance of Silver-spotted Skippers is attributable, in part, to the fact that they are not picky eaters. Adult Skippers feed on nectar and are found in a wide variety of habitats. Skipper larvae are versatile vegetarians, feeding on many different host plants.

Skipper eggs are usually laid singly upon a leaf. Upon hatching, the instar (larva) chews 2 parallel channels in the blade of a leaf to form a flap. The flap is then folded over and secured with silk, creating a snug little tent. By day, the caterpillar hides within this leaf tent. It emerges at night to feast on leaves, eventually growing up to two inches long. As the larva grows, newer and more elaborate tents are constructed, sometimes involving multiple leaves. (Weiss et al.2003, Lind et al. 2001) The tent, however, only partially protects the larva. Some wasp species are adept at visually identifying folded leaves and extracting the juicy caterpillar within.

Other wasp species are able to hunt down caterpillars by the scent and chemical signature of the caterpillar’s frass (caterpillar poop). Thus, a skipper larva must never poop in its own tent! As always, Mother Nature has come up with an innovative solution to the problem; ballistic pooping! Skipper larva are equipped with a special comb’ which latches the anus shut. Once a frass pellet is pushed into the ready’ position, the caterpillar contracts its rear legs, thus increasing its blood pressure by up to 1 pound per square foot! Warning! Warning! The comb finally releases and ZING! The frass pellet shoots out of the caterpillar and rockets out through the door of the leaf tent. Frass ejected in this way travels at high velocity up to 5 feet or 38 body lengths! (Weiss et al. 2003-2006, Caveney 1998)

In fall, mature caterpillars, still hidden in leaf tents, produce brown pupa, often secreting a powder to keep themselves dry. Baby powder for bugs! Isn’t it amazing how Mother Nature thinks of everything? Each pupa and tent eventually falls to the ground with the brown leaves of autumn and remains there until spring. As the weather warms in spring, a winged adult Silver-spotted Skipper emerges from the pupa, intent on mating and laying eggs for the next generation.

For more detailed information on Skippers, including identification, try “Butterflies of the East Coast” by Rick Cech and Guy Tudor.

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The Secret Lives of Insects #3

May 7, 2021 By crm

Syrphid Flies: "Have you Hugged a Flower Fly Today?"

By Judy Ferris, ACLT Guest Blogger

As springtime bursts into bloom, you may have noticed tiny bee-like insects hovering amongst your flowers. Many of these little insects wear convincing yellow and black bee costumes. You may wonder “What are they?” And more importantly “Do they sting?”

In fact, these gentle creatures are Syrphid Flies [pronounced SUR-fid, as in the Beach Boys’ smash hit “Syrphid USA”]. Also called Flower Flies. Their colors alone scream “I’m bad! Very bad!”. But their bee-like disguise is all a bluff. Flower flies have no stinger, no venom, and cannot bite. Any bird that has been stung by a wasp or a bee is likely to avoid repeating that mistake. Thus, the yellow and black warning colors of Flower Flies scare predators into leaving them alone. Flower flies, then, operate under the radar and get a free pass from many predators in your garden!

Adult Flower Flies range in size from 1/3 to 1 inch. They are often called Hover Flies for their ability to hover in place and even fly backwards! Both are rare skills in the insect world. Thus, hovering itself is a clue to Syrphid fly identification. Adult Syrphids feed on nectar for energy and pollen for protein. They are excellent pollinators; in some crops even out-performing bees! Their attention, however, is focused on mating and egg-laying. Female Flower Flies lay tiny, white, football-shaped eggs near thriving aphid colonies. (I can just hear you groaning “Oh no! Here we go again with those poor aphids!”) Some evidence suggests that female Flower Flies can actually dole out the proper amount of eggs proportionate to an aphid population. Just enough larvae will hatch to control the aphid outbreak. Wow! Flies that can do math!

Eggs hatch in about a week and the leech-like larvae set to work. Syrphid fly larvae are nocturnal predators of small insect pests. They snooze by day, then awaken after dark to wreak havoc on aphids, thrips, scales, and caterpillars of both butterflies and moths. Blind and legless, the larvae stumble in the darkness until they bump into something edible. The mouth of the larvae is equipped with an efficient hook, typical of many fly maggots, which is used to grab prey. The hapless victim is thus lifted overhead and held up off the surface as it is gulped from the hook.

According to Michael Raupp of the University of Maryland, a single Syrphid fly larvae can eat more than 25 aphids per day and an estimated 200 aphids in the course of their development. With a healthy balance of maggots and aphids, 75% to 100% of the aphids can be controlled. For a fascinating 2-minute video of a Flower Fly larva chowing down on aphids, click on the link below. Keep your eye on the lower left corner of the video for clueless aphids.

How do you get this aphid-chomping action in your garden? To attract Flower Flies, grow the plants they love! Composite blooms – Yarrow, Queen Anne’s Lace, cornflowers, parsley, carrots, coriander, dill, and fennel are Flower Fly favorites. Syrphids are particularly attracted to white and yellow flowers.

The fortuitous combination of pollinator and pest-remover make the gentle Flower Fly your ideal garden companion! Look for these small visitors where flowers bloom. With luck, you may spot more than one species of flower fly; each identifiable by its unique color pattern. It almost goes without saying; if you see aphids, skip the pesticides and allow Mother Nature to work her magic instead. And don’t forget to hug a Flower Fly today!