Tag Archives: caterpillars

Caterpillar Clusters

Posted on by
8

Groups tend to be more extreme than individuals.

~Daniel Kahneman

In spite of the heat and humidity (or maybe because of it), this is one of my favorite times of year – caterpillar time. The period between mid-August and mid-September tends to be the best time to find the greatest variety of interesting caterpillars in this part of the world. Most species are nearing the end of their larval life and are getting larger, the amazing parasitoids and predators are reaching a peak, and many of the caterpillars are getting ready to pupate, which usually means they will be on the go looking for a suitable spot making them more likely to be encountered out in the open.

_

Caterpillars clustered on an oak leaf (click photos to enlarge)

This past week I had a few nice encounters with a bizarre behavior – caterpillar aggregations (or clusters). The first was a group of Datana sp. (they can be tough to tell apart) larvae clustered on the back of an oak leaf in front of one of our buildings at work. Garden staff had alerted me to them so I walked over and grabbed a couple of quick pics in between what has been constant rain these past two weeks.

_-2

Aggregation of walnut caterpillars on tree trunk

The next day, I checked on the oak leaf, and the cluster was still there, huddled together. I wasn’t sure whether it was the weather, or perhaps an impending molt, causing this behavior. When I got back to my office, another coworker texted me a photo of what looked like a blob of caterpillars on a tree trunk next to her car. This one was a bit more dramatic (as she said, it looked like a squirrel had been squashed on the side of the tree). This group looked like walnut caterpillars, Datana integerrima. They are hairier than the other species from earlier in the day, and this species feeds only on trees in the Juglandaceae family (black walnut, hickories, pecans, and butternut).

_-3

The pile of larvae was huge and several caterpillars thick

This species is known to form large aggregations, often 2 or 3 caterpillars deep, on tree trunks (this larval pile was about 12 inches long and wrapped about 5 inches around the hickory trunk). It turns out this is a phenomenon called synchronous molting, and is fairly common in several species of Datana larvae. I looked online for information on how they manage to coordinate the timing of their molt, but was unable to find a definitive answer. I assume they are able to communicate with pheromones which may impact hormone levels that trigger the molt.

_-4

A close-up view of the hairy mass

This process may take a couple of days before they finally shed and head back up into the tree to continue feeding. But why do these caterpillars cluster? Looking through several resources it seems there are a few theories: thermoregulation (clustering together increases body temperatures of the individuals); feeding advantages (feeding together in groups may help overwhelm plant defenses); and the most likely, anti-predator/parasitoid defense. Datana larvae typically display a defensive U-shape, raising the tip of the abdomen and arching the head and thorax back. They exude what is presumably distasteful liquid if the threat continues. They also exhibit synchronized head-flicking in response to an approaching flying predator or parasitoid. The time just before and after a molt is a very vulnerable one for caterpillars, so it makes some sense to aggregate and combine defenses, although it may also make them more vulnerable to being discovered by certain caterpillar-seekers like hungry birds or curious humans.

Walnut caterpillar sheds

Shed skins of walnut caterpillar cluster (compare to second photo above)

After work that day, I decided to go back out to the walnut caterpillar cluster for a few more photos. As I approached, I could see something was different. The cluster was not as noticeable as I approached their tree. They had all shed! The cluster now looked like a week-old squirrel carcass stuck to the tree, and almost all of the caterpillars were gone, presumably up in the canopy feeding. What a difference a few hours made. As I looked at the pile of shed skins, a slight movement caught my eye a few inches away from the heap of husks…a line of small caterpillars clinging to a green briar (Smilax sp.) vine,

Turbulent Phosphila early instars

Early instar turbulent phosphilas on Smilax sp.

These little guys are turbulent phosphilas, a favorite of mine, both for their odd name and their strange color patterns. I am more familiar with their latter instar where they are adorned in bold black and white stripes and more prominent fake eye spots that make it hard to discern which end is which. Learn more about them in an earlier blog post. I am glad to find these small larvae. Maybe a few will make it until BugFest (coming up September 15!).

I walked over to the other caterpillar cluster on the oak. They had also molted after at least two days of hanging out on that one leaf.

Datana on oak just after shedding wide view

Newly molted Datana sp. larvae on oak leaf (compare to first photo above)

I am still not quite sure which species of Datana these are…most likely either Contracted Datanas, D. contracta, or Yellow-necked caterpillars, D. ministra.

Datana on oak just after shedding side view

Arched defensive posture of Datana larvae

As I maneuvered the branch for a better photo, the cluster began to twitch and assumed the defensive U-posture common to this genus. Teamwork against a perceived threat.

Datana on oak just after shedding

Cozy caterpillars

Though they looked content all gathered together, I assume they eventually dispersed back up into the leafy regions of the tree. I am thankful to work in a place with such biodiversity and that these larval congregations were all in places so accessible that they allowed me to share a few moments of wonder with them.

A Fondness for Caterpillars

Posted on by
8

And what’s a butterfly? At best, He’s but a caterpillar, drest.

~John Grey

Another season of caterpillar finds and larval programs is winding down. We have been searching high and low for larvae and, consequently, caring for a menagerie of crawling critters for several weeks now. My caterpillar programs have ended, and Melissa’s will be finished later this week. Our charges have been oohed and aahed over by hundreds of wide-eyed learners at a series of events at the North Carolina Botanical Garden, the museum’s BugFest, and a well-attended (and well-run) Master Gardener’s conference in Greensboro. These little guys have really earned their keep this past month. Many have pupated in preparation for their long winter’s nap, others have been (or will be) released back into the wild, and, sadly, many have succumbed to a variety of parasitoid wasps. It is somewhat shocking how many caterpillars meet this fate, but I suppose it is one of the main reasons we are all not knee-deep in frass (caterpillar poop) by the end of the summer.

So, this post is to say thank you to all the marvelous Lepidoptera larvae that have graced us with their beauty and fascinating behaviors these past few weeks. Their variety of “attire” and striking forms are just one of the reasons that I have developed such a fondness for caterpillars over the years. Here are a few of the stars of this caterpillar season…

Hog sphinx green

Hog sphinx on wild grape (click photos to enlarge)

Hog sphinx 1

Same hog sphinx, later instar

Waved sphinx?

Waved sphinx on ash

Rustic sphinx

Rustic sphinx on beautyberry

pawpaw sphinx

Pawpaw sphinx deciduous holly

Hummingbird sphinx larva

Hummingbird clearwing on possum haw

Four-horned sphinx

Four-horned sphinx on river birch

Yellow-haired dagger

Yellow-haired dagger, early instar

Hoary alder dagger

Hoary alder dagger moth on tag alder

Retarded dagger moth

Bantam maple dagger on maple

Salt marsh caterpillar?

Salt marsh caterpillar

unid parasitoid pupal mass from salt martsh caterpillar

Strange, communal pupal case of parasitoid wasps that emerged from the salt march caterpillar

Black-etched prominent whipping tails

Black-etched prominent “whipping its tails” as a defense

unid early instar prominent

Mottled prominent, early instar, on oak

White-barred emerald

White-barred emerald, a wonderful twig mimic, on oak

Purplish brown looper larva - twig mimicg

Purplish-brown looper, a huge twig mimic with a head capsule that resembles a leaf bud, on sweetgum

Imperial green

Imperial moth on sourwood

Smaller parasa

Wavy-lined heterocampa just after a molt (you can see the thoracic antlers of the early instar on the shed skin), on wax myrtle

Stinging Rose Caterpillar and shed skin

Stinging rose caterpillar about to eat its shed skin (I accidentally touched this guy at BugFest and felt a mild bee sting sensation for about 45 minutes), on persimmon

Puss Moth caterpillar shedding its skin

Puss moth caterpillar shedding its skin (note color change), on wild cherry

Spiny oak slug

Spiny oak slug on witch hazel

Smaller parasa 1

Smaller parasa on ironwood

Nason's slug

Nason’s slug on oak

Io moth caterpillar

Io moth on hickory

Black-waved flannel moth early instar

Black-waved flannel moth, early instar

Black-waved flannel moth later instar

Same black-waved flannel moth, later instar

Skiff moth larva on cherry

Skiff moth, last instar, on wild cherry

Skiff moth larva approaching pupation

Same skiff moth, getting ready to pupate

Viceroy chrysalis

Viceroy butterfly chrysalis

Monarch chrysalis

Monarch butterfly chrysalis

 

 

 

 

 

 

BugFest Residue, Part 2

Posted on by
2

Nature, in her blind search for life, has filled every possible cranny of the earth with some sort of fantastic creature.

~Joseph Wood Krutch

Here are a few more of the fantastical critters from our scouring of the woods and fields for BugFest…

Polyphemus moth caterpillar

Polyphemus moth caterpillar (click photos to enlarge)

The stars of this year’s caterpillar table were several huge polyphemus moth larvae. We found them on oak, river birch, and red maple this year, and found several on trees at a Chatham County wholesale native plant nursery, Mellow Marsh Farm.

Polyphemus moth caterpillar head shot

These large larvae are eating machines

I was happy that only one of these eating machines began to pupate before the big day, since it is always a treat to share some of our larger species with the crowds.

Smartweed caterpilar

Smartweed caterpillar

One of the more striking species we usually find is the smartweed caterpillar. And this year, we actually found it on smartweed (although I think it crawled off to something else when I took this photo), instead of the usual cattail.

Snowberry clearwing freshly shed

Snowberry clearwing

We borrowed a coral honeysuckle plant from a nearby native plant nursery, Cure Nursery, because it was loaded with feeding snowberry clearwing larvae (these become bumblebee mimic day-flying moths). I caught this one right after it shed (you can see the head capsule just under its legs, and the old tail spike lying with the whitish shed skin behind the caterpillar).

Nason's slug underside

Underside of Nason’s slug caterpillar

The slug caterpillar group is one of my favorites because of their bizarre shapes and colors. We had a Nason’s slug in a petri dish and it obliged by sitting upside down all day so people could see why it is called a slug caterpillar (they lack paired abdominal prolegs that other caterpillars have; they glide rather than crawl).

Crowned slug

Crowned slug

One of the more fantastical of the group, the crowned slug, is ringed by what look like feathered tentacles armed with stinging spines. These are always a treat to find and share.

Spiny oak slug

Spiny oak slug

One of the most striking in terms of color from this year was this spiny oak slug. It is a species that can be quite variable in color, but all are beautiful.

Smaller parasa 1

Smaller parasa

My favorite find was one that didn’t last long enough for other people to enjoy it (it pupated the morning of BugFest). But, to be honest, it probably meant more to me than it would have to a lot of other people. Melissa spotted this (somehow) above our heads on a back lit leaf. When we pulled the branch down to see if it was even a caterpillar she had seen, I knew immediately what it was. I had seen it in the field guide a couple of years ago and had wanted to find one ever since (yup, I am a caterpillar nerd for sure).

Smaller Parasa 1

Smaller parasa moth from two years ago

That page in the book caught my attention when a small beautiful moth came to my window one night a couple of years ago. The gorgeous green helped me identify it as a smaller parasa moth. But when I saw the caterpillar, I really wanted to find one. Well, two years later…

Smaller parasa

What a cool caterpillar!

Good things really do come to those who wait.

What a Way to Go

Posted on by
Reply

Nature is so much worse than science fiction.

~Quote attributed to a student in an introductory entomology course

We discovered a small caterpillar last week that was adorned with some unusual accessories, and that usually isn’t a good thing if you are a caterpillar. I think it was either a variable oakleaf, or a double-lined prominent caterpillar. Both are common species that feed on a wide variety of trees and shrubs.

Variable oakleaf caterpillar with parasites

Caterpillar adorned with green accessories (click photos to enlarge)

I have seen these bright green baubles attached to a few other caterpillars over the years, and it never ends up well.

Variable oakleaf caterpillar with parasites close up

Not the type of fashion accessory you want if you are a caterpillar

They really are beautiful in shape and color when you take a closer look. The first time I saw a caterpillar with these green blobs on its side was a few years ago. I thought they might be some sort of strange cocoon of a parasitic wasp. I was close…they are actually the larvae of a tiny parasitoid wasp in the family Eulophidae.

eulophid-wasp-pupae

Eulophid wasp pupae next to the dead host caterpillar

After watching the caterpillar for a few days, I came back to find a strange array of tiny black blobs near the shriveled caterpillar carcass.

eulophid-wasp-pupae-1

The small piles of yellow “stones” near the pupae are actually waste products

When I looked at my macro images, the small black blobs looked like some sort of macabre lawn recliner, with a tiny pile of rocks at the base. The black blobs turned out to be wasp pupae lying on their backs, and the piles of rocks are the waste products excreted by the wasp larvae prior to pupating. These are parasitoid wasps in the genus Eulophis. They feed inside their caterpillar host, mature, and then pupate in a group near the carcass of their victim. The excellent reference by Eiseman and Charney, Tracks and Signs of Insects and Other Invertebrates, refers to these bizarre creatures as “tombstone pupae”.  I find a lot of these clusters of Eulophis pupae on the undersides of sycamore leaves this time of year.

Caterpillar with Euplectrus pupae

Another strange way to go

A few days ago I found another caterpillar that had met what seemed like an unusual death.

Caterpillar with Euplectrus pupae 1

At first, I thought a fungus had attacked this caterpillar

The fuzzy texture initially caused me to think some sort of fungus had killed it.

Euplectrus wasp pupae

And what are these tiny black pellets?

But when I knelt down and took a closer look, I could see what looked like pupae inside the fuzz, as well as some tiny black pellets or balls stuck to the threads. What the heck is this? Going back to my reference book (mentioned above) for all things strange in the invertebrate world, I found a plausible answer. This caterpillar had been killed by another type of parasitoid wasp in that same family, but most likely in a different genus, Euplectrus. These larvae tend to form a cluster on the dorsal surface of the living caterpillar. When they finish feeding, they move to the underside of their deflated host, and arrange themselves in a row, and prepare to pupate. They create a gauzy, web-like cocoon, which attaches the caterpillar remains to the plant and provides a protective covering. The black pellets are the meconium, or waste products, cast out by the prepupa. It looks as though there wasn’t quite enough room under the carcass for all the wasp larvae to pupate, so some had to be elsewhere in the fuzzy covering.

How bizarre…and it is all happening just outside my door!

 

 

In an Instant

Posted on by
4

Nature taking its course – hunter and prey, the endless circle of life and death.

~Stephanie Meyer

Melissa found some cool caterpillars on a Viburnum this weekend while we were walking in a city park in Richmond.

hummingbird clearwing larva

Hummingbird clearwing caterpillar on Viburnum sp. (click photos to enlarge)

I walked over to take a look and saw a beautiful hummingbird clearwing larva, Hemaris thysbe, in the classic defensive pose of most sphinx moth caterpillars – front of body reared up, head tucked in, body aligned along the twig or mid-vein of a leaf. Suddenly, a huge European hornet, Vespa crabro, appeared and went straight for another caterpillar on the shrub, another hummingbird clearwing.

European hornet attacking caterpillar

European hornet attacking a caterpillar

I managed two quick pictures, and the hornet flew off, carrying its prize back to its nest, where the defeated caterpillar was sure to be chewed up and fed to some hungry wasp larvae. We just stood there, amazed at what we had witnessed. When I looked at the image the next day, I noticed there was another, smaller caterpillar on the same leaf (look just to the left of the clearwing’s “horn” and you can see another small, green caterpillar).

European hornets first appeared in the United States in the mid-1800’s and have since spread throughout most of the East. They look like a very large (up to 1.5 inches) yellow jacket, but are more brownish yellow in overall appearance. We didn’t have time to stick around, but I would not be surprised if that same hornet didn’t come back and search that shrub again, perhaps finding one or more other victims to carry back to the nest. Amazing how a scene in nature can change in an instant.

Leading a Double Life on the Edge

Posted on by
Reply

There is more both of beauty and of raison d’etre in the works of nature- than in those of art.

~Aristotle (384 BC-322 BC)

The adaptations of insects in our yard are both beautiful and incredible. Here is a little more on some leaf edge caterpillars discovered the past few days…

Double-toothed prominent

Double-toothed prominent on elm leaf (click photos to enlarge)

One of the most exciting finds was a group of double-toothed prominent caterpillars (Nerice bidentata) on an elm sapling. These guys are amazing in that they have noticeable fleshy “teeth” on their dorsum that mimic the double serrated leaf edge of elm leaves, their host plant.

Double-toothed prominent early instar 1

Early instar of double-toothed prominent larva

Several of them molted over the past few days and I noticed what seems like a slight change in behavior between the different sizes. The smaller larvae are somewhat darker in color and seem to feed along the leaf edges in a more exposed position.

Double-toothed prominent on small leaf

Their color and pattern aids in the deception

The brown tips of the prolegs match brown spots along the mid-vein of the leaf.

Double-toothed prominent close up

Later instar

Larger larvae appear lighter in color, and seem to feed at an angle that puts them slightly under the leaf. The leaf underside is lighter in color than the top, so maybe this is why. The larvae also have angled stripes along their sides which mimic the venation of the leaves, adding to their effective disguise.

Double-lined prominent

Double-lined prominent on elm leaf

While looking at other elm saplings, I came across another species that seems to mimic both the leaf edge and the twigs of its host plant. When viewing the dorsal surface of a double-lined prominent (Lochmaeus bileneata), the reddish-brown color resembles an elm twig.

Double-lined prominent 1

The light stripes may mimic the leaf petiole

When viewed from the side, the white and yellow stripes along the cater[pillar’s body look like the mid-vein of a leaf, and the brown resembles dying leaf tissue.

Double-lined prominent 2

Even the head stripe helps in the disguise

The feeding position (head towards the tip of the leaf, body along the mid-vein) reinforces the effectiveness of the cryptic pattern and colors, with even the stripes on the head capsule resembling part of the angled leaf venation. I suppose it should come as no surprise that I can spend hours wandering around the yard, amazed by the small wonders all around me. I hope you all can spend some time outside this holiday weekend and discover wonders of your own.

Life on the Edge

Posted on by
Reply

In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment.

~Charles Darwin

Unicorn caterpillar wide view

Unicorn caterpillar positioning itself in a portion of the leaf it has eaten (click photos to enlarge)

I shared some images last week of one of my favorite moth larvae, the unicorn caterpillar. Their shape, coloration, and behavior allow them to blend in remarkably well with their environment. Turns out, they are not alone in their ability to hide in plain sight along the edges of leaves. It is a common strategy of many caterpillars, and I was delighted to find a few other species of leaf edge mimics in the yard over the past few days.

Wavy-lined heterocampa wide view

Wavy-lined heterocampa on hophornbeam leaf

One of the more remarkable leaf edge look-alikes is the wavy-lined heterocampa, Heterocampa biundata. It is variable in color, but frequently has brick red and white splotches along its sides that resemble necrotic leaf tissue. I assume this is a particularly effective camouflage for species that live during late summer and early autumn when many leaves are pock-marked by such splotches.

Wavy-lined heterocampa

Blending in to a hickory leaflet

This species is a generalist feeder on a variety of woody plants (I found them on two species of trees here in the yard). In addition to the leaf splotch patterns on their sides, they tend to align themselves along leaf edges in the areas of leaf they have devoured. The slight bump along their dorsal surface outline helps with this camouflage by making them look more like a leaf edge contour.

Chestnut Schizura on Viburnum nudum side view 1

It requires a careful look to pick these leaf edge mimics out of the background of green

Another excellent leaf mimic is the chestnut schizura, Schizura badia. I found a few feeding on the leaves of a possumhaw, Viburnum nudum. They tend to place themselves inside the outline of portions of a leaf they have consumed, once again making for a well-camouflaged caterpillar.

Chestnut Schizura on Viburnum nudum side view

A closer look

They also have brownish splotches that mimic dying leaf tissue.

Chestnut Schizura on Viburnum nudum

Dorsal view

This species is characterized by a diffuse yellow saddle over the dorsum of the abdomen and a large, irregular-shaped, brown patch on the sides.

Chestnut Schizura on viburnum leaf

A close relative of the unicorn caterpillar

It is a close relative of the unicorn caterpillar and also has the ability to shoot a blend of acids at would-be predators. The defensive spray comes from a thoracic neck gland and can be shot a distance of up to several inches.

Small-eyed sphinx caterpillar on cherry wide view

Small-eyed sphinx larva

Although not a leaf edge mimic per se, the other species I found yesterday does a good job of looking like a common leaf pattern on its host, wild cherry. I am pretty sure this is the first of its kind I have found in my years of caterpillar hunting. It is a small-eyed sphinx, Paonias myops.

Small-eyed sphinx caterpillar on cherry

The red splotches mimic leaf spots on wild cherry

The red splotches certainly are excellent mimics of the pattern on the underside of many wild cherry leaves this time of year. The behavior of this species helps with this deception  as it tends to stay underneath leaves (where the leaf splotches are most noticeable) during the day and then comes out to feed mostly at night. Wagner, in his excellent reference, Caterpillars of Eastern North America, wonders if the spots are more apt to occur on individuals feeding in the autumn, when cherry leaves tend to have more splotches. I continue to be amazed at the intricacies of nature found just outside our door. More on some other leaf edge larvae in my next post.

Seeing the Wild in Wild Cherry

Posted on by
2

The most beautiful gift of Nature is that it gives one pleasure to look around and try to comprehend what we see.

~Albert Einstein

There is a wild cherry (Prunus serotina) sapling just outside our screen porch that is a favorite spot for all sorts of natural events. Wild cherry is a great host plant for a variety of moths and butterflies so I let this young tree grow in a spot too close to the house to ever reach any height just so I can keep track of the comings and goings of its tenants. It has been a busy place these past few days.

red-spotted purple early instar

Red-spotted purple early instar larva (click on photos to enlarge)

Throughout the year, I can always count on seeing some sign of one of the primary occupants of this species of tree, the red-spotted purple butterfly, Limenitis arthemis. They lay their eggs at the tip of cherry leaves, and the larvae feed on the leaves through their entire caterpillar and chrysalis stage, appearing as bird poop mimics. And they even overwinter on the plant, with the third instar larvae of the fall generation making tiny sleeping bags, or hibernacula, by cutting away much of a leaf and rolling the base into a hollow tube where they spend the winter. Next spring, when the cherry leaves first sprout, the tiny larvae will emerge form their tube, begin feeding on the fresh leaves, and begin the whole cycle again. In the photo above, the larvae has already attached the leaf to the twig with silk (so the leaf fragment remains on the tree all winter) and is just beginning to curl the base of the leaf with even more silk (silk strands shrink as they dry, pulling the leaf together).

red-spotted purple hibernaculum 1

One day later, a hibernaculum!

By the next day, the larvae had finished constructing its hibernaculum and was resting inside. I’m a bit surprised it has constructed this so soon as there is still plenty of time for it to grow, pupate, and start another generation before cold weather. But, there are not many leaves left on this tree at this point, so maybe caterpillars can take a cue from food availability and go ahead and go into a resting phase for the winter.

red-spotted purple last instar

Last instar red-spotted purple caterpillar on a different sapling

On a nearby cherry sapling, I found a much larger red-spotted purple larva which will soon, no doubt, form a chrysalis.

white-marked tussock early instar

White-marked tussock moth larva, early instar

Back at the original tree, there were a couple of other caterpillars to observe. One of my favorite finds this time of year is the white-marked tussock moth caterpillar, Orgyia leucostigma . They remind me of a combination caterpillar and toothbrush, due to the four prominent tufts protruding near the head, plus the two black-colored tufts of setae out front that resemble some fancy flossing tool.

white-marked tussock just after molt

White-marked tussock moth larva and shed skin

Nearby was another one that had just molted. This species is a generalist feeder, so I find it on a variety of plant species around the yard.

Unicorn caterpillar second instar

An early instar unicorn caterpillar

Nearby was another of my favorites, an early instar of the unicorn caterpillar, Schizura unicornis. These guys do an amazing job of blending in with the edges of the leaves of whatever they are feeding on. As I looked around, I found a few more…and that will be some fodder for my next post.

 

Summer Cats

Posted on by
3

Nature will not be admired by proxy.

~Winston Churchill

Seems as though my schedule (and the heat) have kept me from some of my usual yard patrols, so I finally went out the other day for a walk-about to see what I could see. It started with my eye catching something out of place on a hickory sapling near the gate…a bright green spot at the edge of a leaf…

Caterpillar head

Caterpillar head peaking out from behind a leaf (click photos to enlarge)

When I walked over, I could see by the distinctive triangle-shaped head, framed by a pair of yellow stripes, that it was an old acquaintance – the larva of a walnut sphinx moth, Amorpha juglandis.

Walnut sphinx larva

Walnut sphinx larva feeding on hickory leaf

I did a short blog post on this cool species a couple of years ago when I found out it has an unusual ability…it is one of the few caterpillars that can make sounds! Researchers discovered it can make a high-pitched whistle by quickly expelling air out of its eighth pair of spiracles (the small breathing tube holes along the sides of caterpillars). Studies have shown that the sound may be enough to scare off potential bird predators.

Walnut sphinx larva 1

The walnut sphinx larva is distinctive in its appearance and abilities

Even though I probably disturbed this little guy while taking its picture (they usually feed on the underside of leaves so I had to flip him over for a full profile pic), I heard no whistle. I can’t decide whether their sound is outside my range of hearing (like many warblers) or these caterpillars just realize I am a long-time fan of their kind and present no threat. After photographing this species, I decided to walk around for a few minutes to see what else I might find.

Walnut caterpillars

Walnut caterpillars

Just a few feet away on another hickory sapling, I found an aggregation of strange, hairy larvae that turned out to be walnut caterpillars, Datana integerrima. What made me notice was a couple of leaves that had been heavily chewed. As I got closer, I could see something that looked like my barber had glued some of my trimmings all over a couple of black worms. When I touched the leaf, they quickly arched into a c-shape, a classic defense pose for members of this genus of caterpillars.

Walnut caterpillars 1

The larvae had just molted

I flipped the leaf to get a better look and found that they had all just molted. This is typical for this species, which is known to move down out of the trees where they are feeding in masses in order to molt. Walnut caterpillars generally have at least two generations per year in the south and can periodically be serious defoliators of localized populations of black walnut, pecans, and various species of hickory. I have never seen them cause significant problems in this area as they seem to be controlled fairly well by natural predators and parasites.

So, in just a few minutes time just outside my door, within a span of less than thirty feet, I was rewarded with glimpses of two fascinating species that share my habitat. It is always good to be reminded that to really enjoy nature, you have to be out in it.

 

 

 

 

 

When Worms Aren’t

Posted on by
1

The worm poop is raining down like a black sleet storm. Got to remember not to open mouth while looking up.

~Ken in Texas, on Unofficial Allis Chalmers Forum, talking about Catalpa Worms

A little over a month ago, I received an email from a neighbor about some caterpillars that were “munching their way thru one of our catalpas”, along with a photo. He also mentioned he had heard these were considered “the gold standard of live bait.” And he was right, they were, indeed, the famed “catalpa worms” (also called catawba worms), a species I had always wanted to see up close. I had seen evidence of their feeding many times, but the caterpillars were always too high up in the tree to photograph. As luck would have it, time slipped away and I did not get down to my neighbor’s place in time to see that batch of caterpillars. But, last week, I went down to get a couple of plants at his nursery (Cure Nursery, a native plant nursery) and was stunned to see another group of early instar caterpillars on those same Catalpa trees.

Catalpa tree branch showing caterpillar feeding

Catalpa tree branch showing caterpillar feeding (click photos to enlarge)

I was stunned because I always assumed there was only one generation per year, as the few trees I have seen around here are always stripped of all their leaves by June or July. In fact, the caterpillars will probably not survive on my neighbor’s trees because the leaves have all been stripped and have barely started to leaf out again. Those few leaves will surely not be enough feed all of these caterpillars. So, I gathered a few of the larvae up and managed to collect a few leaves from sapling sprouts at another roadside location.

Catalpa Sphinx are colonial feeders

Catalpa Sphinx are gregarious feeders in early stages

These boldly patterned larvae are actually the caterpillars of the Catalpa Sphinx, Ceratomia catalpae. Female moths lay large clusters (sometimes numbering in the hundreds) of eggs only on Catalpa trees. Early instars of the larvae feed in groups, turning to solitary feeding in their later stages.

Catalpa Sphinx larva

Catalpa Sphinx larva

As with most members of the Family Sphingidae, the larvae are adorned with a prominent tail spike, which seems exaggerated on the early instars.

Catalpa Sphinx pair of larvae 1

Pair of feeding larvae

Catalpa Sphinx larvae heads

They are eating machines

And, like most caterpillars I have seen, these guys are eating machines. In the short time I was photographing them, just a few managed to consume about half of one of the large leaves I collected. And when they eat, they poop (you can see some frass, caterpillar poop, in the first photo of this pair). So, if you are standing under a large Catalpa tree having perhaps hundreds of large caterpillars up in its branches, I suppose it can sound like rain pouring down. Caterpillars eventually climb down the tree trunk and pupate in the ground nearby. And, surprisingly, it is common to have two or more generations in a season.

Catalpa Sphinx pair of larvae

Fishermen swear by the later stages of these larvae as fish bait

In looking online, it seems the large (up to 3 inches) caterpillars are, indeed, a favorite of fishermen. In fact, their value as fish bait (especially for bass and catfish I am told) was mentioned when the species was first described in the 1870’s. Apparently, the skin is tough enough to hold the larva on a hook better than many live baits. So, whether the caterpillar is a pest when it defoliates your Catalpa, or a valuable commodity, depends on your perspective, as is so often the case when it comes to things in nature. For me, it’s enough to just have the chance to finally see some of these beauties up close.