Archives For Jim Steffen

I am sure that most of you know what I am referring to when I say “leap year.” Although this is not a leap year, I am suggesting that we unofficially call 2015 “Lep Year”—“lep” being short for Lepidoptera (from the Latin “scaly wing”), the order of insects that includes butterflies and moths. It has probably been a decade or more since I have seen the diversity and abundance of butterflies and moths that I have seen this past spring and summer.

PHOTO: Euchaetes egle (Milkweed tussock moth).

These voracious Euchaetes egle caterpillars were shredding some of the common milkweed plants near the prairie at the Garden this summer.

Lately, the butterflies have gotten the lion’s share of PR. In particular, the monarch butterfly is on nearly everyone’s radar, due to its precarious situation with dwindling wintering grounds and lack of larval food plants—the milkweeds. However, if you compare the two groups, butterflies and moths, the numbers of moth species outnumber the butterflies by more than ten to one in North America! In fact, there is a moth species that is also dependent on milkweeds—the milkweed tussock moth (Euchaetes egle). The caterpillars of this species are black and orange (a similar color combination to the monarch), and they usually occur in large numbers when you find them. The black-and-orange coloration signals to predators not to eat these fuzzy little fur balls.

The main difference between butterflies and moths is that the moths, in general, tend to be rather drab colored and active at night while the butterflies are mostly colorful and active during the day. These are generalities since you can find very colorful moths, rather drab butterflies, and a number of day-flying moths. There are also structural differences most easily seen in their antennae. While butterflies have narrow antennae with club-shaped structures at the end, the moths can have either thread-like antennae that end in a point in females or fern-like antennae in males. The fern-like antennae of the males are used to detect the chemicals, called pheromones, released by the females when they are ready to mate. Some moths can follow these chemical trails for miles.

Sixty percent or more of the diet of some nestling songbirds comes from caterpillars, and these are most certainly moth caterpillars.

Moths are not only extremely diverse in shape and pattern, they also have a wonderful variety of common names that people have come up with to label them. There are sphinx moths or hawk moths, daggers and darts, army worms and prominents, sallows and quakers, owlets and loopers, and marvels and bird-dropping moths. The names go on and on, some attempting to describe the adults and others the larvae.

PHOTO: Cecropia moth caterpillar (Hyalophora cecropia).

This brightly ornamented Cecropia moth caterpillar (Hyalophora cecropia) will turn into North America’s largest native moth.

It is hard to say which stage of the moth life cycle is more impressive. Although the adult moths are so varied in their shape, size, and patterns, the caterpillars are no less amazing. Take for example the strikingly beautiful brown hooded owlet moth caterpillar.

PHOTO: Brown hooded owlet caterpillar (Cucullia convexipennis).

The brown hooded owlet caterpillar (Cucullia convexipennis) is a stunning specimen to find outside my office.

It would be difficult to find a more attractive critter anywhere, and here it was, right outside my office. Equally impressive are the huge silkworm caterpillars. The Cecropia moth caterpillar (Hyalophora cecropia) is almost shocking, not only because of its massive size, but also because of the large orange-and-yellow spiky beads covered in black spots along its back and the smaller turquoise-spiked beads ornamenting its sides.

And who could talk about moth caterpillars without mentioning the infamous woolly bear? These orange and black-banded caterpillars are often consulted to see what the winter will be like. Unfortunately, the banding on the caterpillar has nothing to do with the weather, but at least it has gotten it a lot of attention. The woolly bear eventually turns into the bright orange Isabella tiger moth (Pyrrharctia isabella).

PHOTO: Woolly bear caterpillar (Pyrrharctia isabella).

Who hasn’t been tempted to touch the woolly bear caterpillar (Pyrrharctia isabella)? Photo by By Micha L. Rieser via Wikimedia Commons

PHOTO: Isabella tiger moth (Pyrrharctia isabella).

The Isabella tiger moth retains its orange-and-black caterpillar coloring. Photo by Andy Reago & Chrissy McClarren via Wikimedia Commons

The high diversity and nocturnal behavior of moths make it not unlikely that you might find a moth or caterpillar you haven’t seen before. The other day, while trimming my rambunctious Virginia creeper vine on the side of my house, I spotted an interesting caterpillar that I had never seen before. As a woodland ecologist I have experience with a lot of caterpillars, so it is always interesting when something new comes along. As it turns out, the caterpillar was the larval stage of an Abbott’s sphinx moth (Sphecodina abbottii). Although this was a new find for me, I still have not seen the adult moth.

Every morning when I come into work, I check the wall outside our building under the light to see if any new moths have shown up during the night. Some of the moths I have spotted this summer are the Crocus geometer, Colona moth, Ironweed borer, large maple spanworm, Ambiguous moth, green owlet, and one of the microlepidoptera, the morning-glory plume moth.

PHOTO: Colona moth (Haploa colona).

Colona moth (Haploa colona)

PHOTO: Crocus geometer (Xanthotype urticaria).

Crocus geometer (Xanthotype urticaria)

PHOTO: Green owlet (Leuconycta diphteroides).

Green owlet (Leuconycta diphteroides)

PHOTO: Morning glory plume (Emmelina monodactyla).

Morning glory plume (Emmelina monodactyla)

PHOTO: Ironweed borer (Papaipema cerussata).

Ironweed borer (Papaipema cerussata)

Most moths do not live for very long as adults. Ironically, some of the largest moth species live the shortest lives. I had the opportunity to see a new species of one of these megamoths for the first time this summer when my wife brought home an Imperial moth (Eacles imperialis) that she found clinging to the window of the school where she works. The very large moths in the family Saturniidae (silkworms and royal moths) emerge either from the soil, in the case of the Imperial moth, or from one of the familiar large cocoons you can find attached to a twig, like those of the Cecropia or Promethea moths. Since these moths do not have functional mouth parts, they are unable to feed, so they live off their stored body fat while searching for mates until they die, usually within seven to ten days.

PHOTO: Imperial moth (Eacles imperialis).

This Imperial moth (Eacles imperialis), had a 5-to-6-inch wingspan, and a body as big as my thumb!

Interested in finding out more? Visit the Moth Photographers Group at or BugGuide at

Another new species for me was the painted lichen moth. While removing Japanese beetles from my hazelnut shrubs, I spotted what looked like a large firefly. As it turned out, it was not a firefly at all, but rather a moth that mimics one. Since fireflies are toxic to most predators, the moth gets a benefit from looking like the firefly. Another neat trick they employ is a maneuver known as frass flicking. They are able to expel their excrement nearly a foot away from their body. This is important because some predatory wasps locate their prey by homing in on the scent of their droppings.

There are a number of moths—or more accurately, moth larva—that are pests for gardeners. Almost all vegetable growers have run into cutworms at one time or another. Cutworms were given this name because of their habit of cutting off seedling plants in the garden. There are a number of cutworm species native to this country, but all develop into moths later in their life cycle.

PHOTO: Parasitized sphinx moth caterpillar.

The white structures on this parasitized sphinx moth caterpillar are the cocoons of the braconid wasps.

Another familiar larva is the tobacco or tomato hornworm (Manduca sexta). These are the large green larvae of one of our native sphinx or hawk moths. The Carolina sphinx larva is often found on tomatoes. Although they will rapidly chow down on tomato plant leaves, I generally leave them alone until they have had their fill and work their way down into the soil where they pupate to spend the winter. (I find that they rarely put much of a dent in the productivity of my tomato plants.) If you should happen to dig up one of their pupae when turning over the garden soil, they are a dark, shiny brown, pointed at one end, and have what looks like a teapot handle on the side that houses a long, curved proboscis. If you pick them up, you might be startled by the fact that they often times will swivel around at the middle—probably a predator avoidance behavior. Tobacco hornworm and sphinx moth caterpillars commonly fall prey to braconid wasps, which parasitize them. Leaving these parasitized caterpillars in the tomato garden can be an effective method of pest control.

PHOTO: Female gypsy moth (Lymantria dispar).

Female gypsy moth (Lymantria dispar)

A more serious pest species is the introduce gypsy moth. These moths occur in huge numbers and are capable of completely defoliating adult oak trees over large areas. A few years ago, we avoided an invasion of gypsy moths at the Garden when hundreds of thousands of these moths, in Turnbull Woods forest preserve across Green Bay Road in Glencoe, succumbed to a cool, rainy spring.

Join me and take advantage of this Lep Year—check out the yard lights, hedgerows, and flower beds, and see how many moths, caterpillars, and cocoons you can find!

Photos ©2015 Jim Steffen unless otherwise noted.

©2015 Chicago Botanic Garden and

Echoes of a Silent Night

Senior ecologist Jim Steffen describes his close encounters with curious and beautiful bats.

Jim Steffen —  October 29, 2014 — 2 Comments

A few years ago, in early spring, I was traveling through McDonald Woods at the Chicago Botanic Garden, searching for some of the flat-bodied crab spiders (Philodromus) that typically spend the winter in communal groupings under the loose bark of dead trees. Upon reaching a small stand of dead American elm trees, I began to lift the loose remaining bark away from one of the trees to see if any spiders were present.

As I gently pulled the bark away from the trunk, a tiny black hand reached up over the top edge of the bark. It quickly became obvious that there were more than spiders under this bark!

Although I was a little startled to have this hand slowly reach out in front of my face, I immediately realized that this piece of loose bark was the day roost of a silver-haired bat. The silver-haired bat is a medium-sized bat that is a dark chocolate brown or black with white hairs scattered among the dark hairs on its back. I gently released the bark so as not to disturb the napping bat any more than I already had. This is just one example of why it is important to maintain at least some dead standing trees in our woodland communities.

PHOTO: Silver-haired bat.

A silver-haired bat curls up tightly on a tree in McDonald woods. Photo by Jim Steffen

Even though bats are fairly common mammals in our area, since they are almost totally nocturnal, we don’t get to see them all that often—especially at close range, when we would be able to admire their delicate form and attractive appearance. Bats are in the order Chiroptera, roughly translated as “hand wing,” and are the only mammals that are actually capable of true flight (unlike flying squirrels—which we also have at the Garden). 

You might be familiar with another group of small mammals known as shrews. Shrews are mouse-like animals that are actually carnivores that feed heavily on invertebrate populations. Although bats may have varied diets around the world, here they are primarily insect eaters, much like shrews with wings.

When I was in college studying mammology, we used to go out at night and look for streetlights where there were large numbers of moths and other flying insects attracted to the lights. We would then take out our car keys and jangle them around to make high-pitched sounds with the keys clinking together. These high-pitched sounds would simulate the high-pitched sounds produced by the echolocation sounds produced by hunting bats to locate their prey. (Unless we are equipped with special listening devices, we are not able to hear the sound of bat echolocation.) Often times, many of the moths would begin flying erratically, or drop out of the air as though they had been struck with a stupefying charm from Harry Potter’s wand. These moths have evolved defensive tactics to help them avoid being eaten by bats by flying in erratic patterns or closing their wings and dropping if they heard the sounds of an approaching bat. 

PHOTO: Eastern Red Bat

An eastern red bat (Lasiurus borealis) clings to black landscape fabric at the back of one of the buildings here at the Garden. Photo by Jim Steffen

Many years later, while removing invasive garlic mustard from our oak woodland a few summers ago, I came upon an oak tree with a broken branch. All of the leaves on the branch had turned a bright reddish-brown that stood out against the backdrop of all the other green foliage. On closer examination of the branch, I spotted a female eastern red bat hanging upside down, in typical bat fashion, with its single offspring clinging to it. I don’t know if the bat was aware of it, but this dead branch provided the perfect camouflage for her rich color.

This made me think about how these mammals perceive the world. Do bats have color vision, and was this red bat able to tell that the dead branch would be such a good match for its own color? Most nocturnal animals tend not to have color vision, since color does them little good in the dark. Most bats are various shades of brown, black, or gray. (It is a different story for birds that are mostly active during the day and use bright colors as a means of attracting mates or advertising territories.)

PHOTO: Lasiurus cinereus (hoary bat).

Hoary bat (Lasiurus cinereus by Daniel Neal [CC-BY-2.0], via Wikimedia Commons

We have five species of bats that are likely to be seen at the Garden. Some of them are summer residents, like the little brown, big brown, and eastern red bat, while others are mostly migratory species, like the silver-haired and hoary bats that show up during their spring and fall migrations. Years ago, in the late fall, while using fine nets at night to capture owls for attaching U.S. Fish and Wildlife Service bird bands, I often caught many of the large, hoary bats migrating south for the winter. These large bats have an attractive frosted appearance with a mix of white and reddish hairs all over their bodies.

While I was studying birds in the tropical rain forest of Central America, I often encountered small colonies of bats hanging at eye-level, under the broad leaves of Heliconia plants. I think these wide, tent-like leaves were chosen mostly for the protection they gave the bats from the torrential downpours that occurred every day. However, the bats we find here are either solitary animals, like the red, silver-haired, and hoary bats that live solitary lives in the woodlands and forests, or they are colony-forming bats, like the little and big brown bats, that search out attics, barns, or large hollow trees where they gather in groups to raise their young.

Some of the bat species also search out caves or old mine shafts during the wintertime, where the subterranean habitat provides moist, stable conditions with above-freezing temperatures suitable for hibernation. It is possible to construct bat houses that, if placed in the proper locations, can attract and support colony-forming bats during the summer.

We have several of these bat house installed on buildings around the Garden. This summer, one of those houses contained half a dozen bats—probably little browns. It is best to place bat houses in full sunlight, since the bats have high body metabolisms and prefer very warm conditions for roosting during the summer. Think you’d like to build a bat house? Construction details can be found at the Bat Conservation International website at

PHOTO: Flying squirrel.

Another local flier, this very tame flying squirrel enjoyed a snack of walnut with his photo op. Photo by Jim Steffen

Bats are more than curious and beautiful creatures; they are also tremendously important components of a healthy environment. They are extremely important control agents of insect populations. Many of the insect species they eat are harmful crop pests, like army cutworm, or irritating or disease-carrying species like mosquitoes. Some bats can consume more than 1,000 mosquitoes in a single night! Bats are in trouble now for many reasons—not the least of which are climate change, exotic diseases like white-nose syndrome, and habitat loss.

Although bats are seldom seen and often have scary, erroneous wives-tales associated with them, we should be working hard to correct the problems that might lead to a truly silent night.

©2014 Chicago Botanic Garden and

The Earth on its Back

Jim Steffen —  April 8, 2013 — 1 Comment

There is a Native American myth that is believed to have originated with the Onondaga tribe of the Iroquois nation of northeastern North America. It is a creation legend about how the earth (the land) was created. The legend incorporates a number of different animals including swans, pied-billed grebes, muskrats, and many others. The central character in the story is a turtle. The turtle, an island in a world of water, was chosen to carry soil and tree seedlings on its back, which eventually became the land the people lived on. So this story is about preservation and nurturing. Although this legend may have originated with the Onondaga, it is a common myth found throughout many Native American cultures.

The fact that the turtle myth was so widespread across the continent is not really all that surprising when you consider how many different species of turtles there are. There is a turtle species for just about every kind of wetland environment that exists, from sea turtles to bog turtles to  river cooters and pond sliders. There are approximately 17 species of turtles native to Illinois and nearly half of those occur at the Garden.

Other than birds, turtles are among the most common animals you are likely to encounter on any given day during the growing season at the Garden. Like the early blooming wildflowers in McDonald Woods, turtles are truly one of the first signs of spring. Soon after the ice melts on our lakes, turtles begin moving from the bottom of the lakes where they spent the winter hibernating. During the dark days of winter under the ice, turtles are able to slow their bodily functions down to the point where they can obtain enough oxygen to survive by absorbing it through the mucus membranes and tiny capillaries of their throat and cloaca (the common opening for defecation and egg laying). They also use some fascinating chemistry, part of which involves dissolving calcium from their shells to help neutralize toxic acids that would be fatal under normal circumstances. Still cold and sluggish from their long winter sleep, they begin swimming around near the surface, often poking their heads out to take their first real breath of air since descending to the bottom of the lakes in fall.    

Hoop trap for aquatic turtles

Hoop trap for aquatic turtles

Several years ago, I initiated a turtle project with one of the summer interns. We set out to try to determine how many turtles and how many species occur in our lakes. Utilizing a number of different live traps, we were able to count most of the individuals and almost all of the species that can be found here. Over three months, we were able to capture nearly eighty individuals of eight different species.

PHOTO: Floating trap for basking turtles.

Floating trap for basking turtles

The turtles can be divided into two general groups, those that like to bask (sun themselves on logs, rocks, or on the shore) and those that rarely bask. The basking turtles are the species most often encountered at the Garden. The most abundant member of this group is the red-eared slider. 

This is the turtle of dime-store fame. There was a time when it seemed like every kid had one of these sliders as a pet – do you remember Cuff and Link from the movie Rocky? They are distinctive, with a bright red slash along the side of their heads.  Although they are the most abundant species here, they are not native to this part of Illinois. Sliders have been introduced to many parts of the country where they had not previously been found. This is the result of all those dime-store turtles that grew up to be bigger turtles that were eventually released when their owners either ran out of room for them or the appeal of these long-lived animals wore off. Like many introduced species, the slider is aggressive toward our native species and as a result has achieved a dominant place in the turtle population.

PHOTO: The introduced red-eared slider.

The red-eared slider, named for the distinctive red patches over its ears.

PHOTO: False map turtle

Notice the narrow yellow bar on head of the false map turtle.

PHOTO: Underside of false map turtle

Topography-like lines mark the underside of the shell of this false map turtle.

PHOTO: Ouachita map turtle

Notice the square yellow blotch behind the eyes of the Ouachita map turtle.

The slider is not the only introduced turtle at the Garden. Some other species that can be found here that were not known in the region historically include the three-toed box turtle, the false map, common map, and the Ouachita map turtles.

Releasing pet turtles is not a good idea. The slider has greatly changed the dynamics of natural turtle populations all over the country. Some species, like the box turtles, which are terrestrial species that do not hibernate in lakes, are sometimes found at the Garden only after they have died after not being able to survive the winter here. There is also the possibility of spreading diseases.

The native turtles found at the Garden include the Midland painted turtle, Western painted turtle, stinkpot or musk turtle, spiny soft-shelled turtle, and the snapping turtle. The stinkpot and the snapping turtles are members of that group of more aquatic turtles that do not typically bask on logs or rocks. So although the snapping turtle is a common species at the Garden, it and the stinkpot are not seen nearly as much as the basking species.

A spiny soft shell

A spiny soft shell

PHOTO: Closeup of the spiny soft-shelled turtle.

The spiny soft-shelled turtle’s snorkel-like nose.

PHOTO: Western painted turtle.

The western painted turtle

Where do these turtles get their names? The map turtle gets its name from the pattern along the underside of the shell and along its neck and head that looks like topographic lines on a map. The box turtle has a hinged plastron (belly) that allows it to pull its head and legs inside the shell and close the “doors” sealing out predators. 

Soft-shell turtles have a soft, leathery shell that bends and flexes like an old leather baseball mitt. They have a very low profile and look like a large, olive-colored drab Frisbee when they are basking on the lawn.  Painted turtles often have attractive red markings along the edge of their carapace (shell) and plastron. As far as the stinkpot turtle goes, I’ll let you guess why they have that common name. I’m sure that if you do some digging, you’ll be able to sniff out the answer.

The turtles are egg-laying reptiles. Their eggs are probably best described as leathery-shelled ping-pong balls.  During the summer, the adult turtles will haul themselves out along the shore and look for suitable places to dig a hole in which to deposit their eggs. At the Garden, turtles often choose to lay their eggs in the mulch around the tree and shrub planting beds, probably because it is a softer, easier place to dig. This egg-laying season is a dangerous time for turtles.  

PHOTO: Snapping turtle laying eggs.

Snapping turtle laying eggs

During this time they are out of the water, many encounter predators, and often cross roads looking for

PHOTO: Snapping turtle eggs.

Snapping turtle eggs

nesting locations. Once the eggs are laid, the turtle covers the eggs with soil and then retreats to the water, leaving the eggs and young to fend for themselves. Usually the eggs will hatch in 45-90 days, but sometimes, for individuals that lay their eggs too late in the season, they may overwinter.  Although turtles generally lay a good number of eggs (2-40 or more, depending on the size of the individual and species), the failure of those eggs is high due to predators. Skunks and raccoons are probably the two most frequent predators of turtle eggs, but almost any predator that comes across a nest is likely to take at least some.

What do these critters eat? Most species are omnivores. They eat a combination of plant and animal material. The common map turtle specializes in mollusks, like clams and snails that it crushes with its broad hard mouthparts. The spiny soft-shell is a fast swimmer and often feeds on fish. The red-eared slider is also omnivorous, but tends to become more of an herbivore as it gets older. It should also be noted that turtles perform a valuable ecosystem service as carrion feeders by feeding on dead fish and aquatic animals that would otherwise remain for long periods as they decompose. So you can think of turtles as sort of turkey vultures of the aquatic world – the sanitation squad.

Visitors frequently encounter turtles crossing the road at the Garden during the summer. Although the urge is strong to help the turtle back into the lake, don’t approach them too closely since turtle are very good at defending themselves and have long necks that can dart out and grab anyone or anything that gets too close. Turtles have very sharp-edged mouthparts and once they get hold of something, they don’t let go. Many a dog has lost a piece of its nose when getting too inquisitive about turtles.

If you happen to be visiting the Garden in summer and spot a turtle basking in the sun, try to see if you can figure out which species it is. Perhaps more importantly, if you spot a turtle, try to remember the Onondaga legend and the great responsibility bestowed on it to preserve the land and plants for the people.

©2013 Chicago Botanic Garden and

Hidden Wings

Some butterfly species spend the winter hidden away, to emerge in early March.

Jim Steffen —  March 26, 2013 — Leave a comment

A walk in McDonald Woods in late winter or early spring might be uninspiring to many people because of the drab gray trunks of dormant trees and seeming lack of activity. You might see the occasional black-and-white flash of a downy woodpecker flitting from tree to tree, or spot a white-breasted nuthatch as it navigates upside down, probing for whatever bits of protein it might have missed on earlier explorations.  

But who would expect butterflies? After all, 80-degree days and abundant flowers overflowing with nectar haven’t even awaken in our minds. But they are here, at least those few species that spend the winter, hidden away as adult butterflies under loose bark, inside piles of brush, or maybe in an old woodpecker nest or hollow log.  

Even though I know they are here, it is still a surprise the first warm day in March when I spot a mourning cloak basking in the strengthening sunlight. As I approach for a better look, it is likely to spiral upward, erratically flitting off to another patch of sun.  

PHOTO: Side view of the question mark butterfly.

Question mark (Polygonia interrogationis)
© Carol Freeman

The mourning cloak, eastern comma, and question mark are three of the common woodland butterflies at the Garden that generate a brew of chemical antifreeze earlier in fall that allows them to survive the coldest weather winter has to offer. Instead of migrating like the monarch or spending the winter wrapped in a chrysalis, these three are adults, wings at the ready to take advantage of the first warm weather of spring.

The lack of nectar-producing flowers this time of the year does not deter them as they are perfectly happy to feed on sap from any of the branches that may have been damaged during winter storms, or drink the fermented liquid oozing from an injured willow or oak tree. Although butterflies are a generally short-lived organism, usually living only a few weeks, these three can survive for eight to ten months.

PHOTO: The Mourning cloak butterfly.

Mourning cloak (Nymphalis antiopa)
© Carol Freeman

The dark, purple-brown color of the mourning cloak gives it an advantage at this time of the year. Those richly colored wings, held out to the sides, act like solar collectors absorbing the sun’s energy and passing it on to the body where it raises the temperature of their muscles enough to allow them to fly.

The comma and question mark utilize a similar basking strategy. They often posses sun-absorbing, dark-colored under wings, which, when held closed against their bodies and perpendicular to the sun’s rays, elevate their temperature. The thermal boost gives this group of insects a head start on the season by allowing them to exploit a habitat at a time of the year when there are few other butterflies around to compete for precious resources.

Although these three butterflies are insects, and as you know all insects have six legs, these three belong to a group known as the brush-footed butterflies. They have modified fore legs that are smaller than their other legs and cannot be used for walking.

PHOTO: Question Mark butterfly.

Question mark
© Carol Freeman

If you get a chance to get a close look at one of them, you might be surprised to see that they are only standing on four legs. The other two are tucked under their heads.

Next time you think of taking a walk in the dormant woods, pick a sunny day when these not-so-fragile gems might be out and about, soaking up sun and supping on sap.

©2013 Chicago Botanic Garden and

While checking the perimeter fence around McDonald Woods to see if there was any damage to the fence after a windy day, I discovered a large red oak that had lost its foothold in the frozen soil and had toppled over against a white oak. Since the tree was threatening to push the other oak over into the fence, I decided to cut the red oak down to save the white oak and the fence.

When trying to remove a leaning tree, you have to start at the base and work your way to the top as each section falls away. The base of the tree was good and solid, sending a shower of sour-smelling oak shavings flying from the chainsaw. When I got about halfway up the trunk, the saw began spewing dark brown flakes of rotting wood, and the sawing became easier. After a few more cuts, the trunk became mostly hollow and the top of the tree crashed to the ground.

Looking back at one of the middle sections of trunk, where the center was a rich dark brown from the rotting wood, I noticed a thick, white object shaped like the letter “C”.  

Bessbug Grub

A closer look showed the object to be a large grub from a beetle. These grubs are similar to the white grubs of Junebugs and Japanese beetles that you find in your gardens and lawns, but much larger. Although the rotten wood was frozen, I was able to split open the log, revealing a whole colony of 30 to 40 beetle grubs about 2 inches long and about a half inch in diameter. Each grub was cradled in a smooth-surfaced cell in the rotted wood. Even at temperatures well bellow freezing, the grubs were able to move enough to show they were alive.

As it turned out, these grubs were the larvae of one of our largest woodland beetles, known as the stag beetle or stag-horn beetle. These beetles are one of the myriad invertebrates active year-round, doing the important work of reducing fallen trees to rich organic soil that will help other trees grow and support the next generation of plants.

These beetles are members of the Coleoptera (beetles) and get their name from the large antlerlike mandibles (jaws) found on the front of the head of the males.  The females also have mandibles, but they not as impressive as those of the males. The large mandibles are used for territorial defense and also to protect the beetles from any birds or other animals that might try to eat them. The impressive “antlers” can look threatening to people when they first encounter them; however, they are not a serious threat to people and will only give you a pinch if you handle them roughly. It is not uncommon to find the large brown stag beetles around buildings near woodlands at night, when they are sometimes attracted to the lights.

These critters are fascinating, not only because they are social in the larval stage and can take several years to mature, but they can also produce an assortment of sounds that are thought to help with communication between the grubs. The grubs have a striated structure on the leg that allows them to produce sound (called stridulation), kind of like rubbing a spoon on a washboard. If you notice the dark-colored segment that looks distended on the end of the grub, it is the digestive chamber, where the wood the grub consumes is digested with the aid of microorganisms.  If you give one of these guys a gentle squeeze, you will notice a stream of liquified, dark brown wood coming from the tail-end of the critter. 

One last item of interest about these wood-grubbing dynamos is that they often carry a large population of mites around, clinging to their bodies. When I took a closer look at the grubs, I found dozens of whitish-colored tiny mites attached to each of their legs.  

Bessbug mites

This observation lead me to recall the verse by the Victorian mathematician, Augustus De Morgan:

Great fleas have little fleas upon their backs to bite ’em,
And little fleas have lesser fleas, and so ad infinitum.
And the great fleas themselves, in turn, have greater fleas to go on,
While these again have greater still, and greater still, and so on.

These mites do neither the beetles nor the grubs any harm; they are just along for the ride and probably snacking on any choice fecal pellets deposited by the beetles. If you find yourself sitting on a log out in the woods, you just might be perched above a nest of developing stag beetles.  

©2013 Chicago Botanic Garden and