BugFest Residue

If you have a chance to play in nature, if you are sprayed by a beetle, if the color of a butterfly’s wing comes off on your fingers, if you watch a caterpillar spin its cocoon– you come away with a sense of mystery and uncertainty.

~Michael Crichton

BugFest, the NC Museum of Natural Sciences’ premier special event, is over. Somewhere around 29,000 people visited this year, and, as always, we talked to a lot of them about the caterpillars we collected in the days leading up to the event. A lot of effort goes into preparing for the event, by everyone involved. For us caterpillar wranglers, it means finding and caring for a variety of fascinating critters, and then releasing them all back into the wild. Every year we have specimens that never make it to the big day because they either pupate or have been parasitized and die. So, there are many things that our visitors miss seeing. Here is something that only a few us were privileged to witness this year.

mystery-cocoon

Mystery cocoon (click photos to enlarge)

Let’s start with a mystery. I found this cocoon on a leaf in one of the cages with multiple species of larvae we collected right before BugFest. It reminded me of a tussock moth cocoon of some sort since it appears some of the “hairs” from the caterpillar have been incorporated into the cocoon covering. I didn’t have time to do much with it until after the event. I looked at it more closely, and then remembered we had collected a very nice spotted apatelodes (Apatelodes torrefacta) caterpillar who had started to shed its setae the day before BugFest.

spotted-apatelodes-top-view

Spotted apatelodes caterpillar

I was disappointed at the time, because these large larvae are certainly in the cute category of caterpillars, especially if you manage to get a look at their undersides…

Spotted Apatelodes showing red proleg feet 1

This caterpillar looks like it is wearing red socks

They are one of the only larvae I know that dress like a friend of mine from my museum days (you know who you are) and wear outlandishly bright “socks” (in this case, red, instead of the purple ones my friend still wears). When I realized I had not seen the pupa of this particular specimen, I googled it, and there it was, mystery solved – it is a spotted apatelodes cocoon.

I’ll share a few more of the leftovers from our caterpillar collecting efforts in the next post.

Last Larva?

…one’s first impression might be that this creature has somehow lost its way out of an Amazonian jungle.

~David L. Wagner, describing the Crowned Slug caterpillar in Caterpillars of Eastern North America

When I returned from our California trip, I looked around the yard and saw what lies ahead – lots of yard work. Seems as though autumn had arrived while we were away – leaves changing colors and dropping, branches and twigs littering the ground, and an accumulation of acorns on the back deck. This is apparently a good year for the mast crop (acorns and hickory nuts). So, I began by sweeping off the walkway and deck.

bucket of acorns

Cleaning up the acorns on the deck (click photos to enlarge)

The two large oaks out back drop an impressive number of acorns every few years (usually with a resounding clang on the metal roof and deck). I swept up almost a 5-gallon bucket of nuts that had fallen in a week and a half.

Crowned Slug 1

Crowned Slug caterpillar

As I finished sweeping up, I noticed a splash of color on one of the fallen oak leaves – a caterpillar. And not just any caterpillar, one of my favorites, the Crowned Slug (Isa textula). This is one of the more bizarre-looking of the “stinging” caterpillars.

Crowned Slug close up

Close up of stinging spines

This unusual species is characterized by a series of lobes projecting from the sides of the body, each lobe containing an array of long, stinging spines. Additional stinging spines are found in clusters near the middle of the dorsal surface. The head region is marked by two elongate projections edged in red.

Crowned Slug from below

Crowned Slug feeding on dried oak leaf

I was initially surprised to find one so late in the season, and to see it feeding on an obviously dry fallen leaf. But when I looked it up in Caterpillars of Eastern North America, the author said these caterpillars may be active very late in the season, sometimes dropping down with autumn rains and wind. So, I guess it is not so unusual after all.

Crowned Slug

A beautiful way to finish another great caterpillar season

After spending a few minutes photographing it, I placed this late larva on a fresh oak leaf out back. If this is the last larva of the season, it is a memorable one…slug royalty. I’m already looking forward to next year…

Munchies

A caterpillar is basically a flexible tube…it is designed purely for eating and growing.

~Michael Chinery, in Butterflies and Day-flying Moths of Britain and Europe

Eat, poop, eat, poop…such is the life of a caterpillar. After BugFest, I kept a few of the specimens for a couple of days before releasing them back into the wild (where they were found) in order to observe and photograph them. The tough part of rearing caterpillars is providing them with enough of the right kind of food. It can get to be a full-time job if you have too many larvae living with you.

Spicebush Swallowtail larva feeding on Spicebush leaf

Spicebush Swallowtail larva feeding on Spicebush leaf (click photo to enlarge)

Some are picky eaters, like the Spicebush Swallowtail larva above (eats Spicebush and Sassasfras in our area), and feed on only one or two species of plant. Others are generalists, and can be found on a wide variety of plants, but some may prefer whichever plant species they were originally eating.

Whatever the diet, they tend to eat relatively little when small (first couple of instars). But, as they grow and molt, they really become eating machines. It is tough to find data on how many leaves one caterpillar can eat but one reference on monarchs estimated a single larva could consume all the leaves on a Common Milkweed plant by the time it was ready to pupate. Certainly, the last instar of a Monarch larva can consume 4 or 5 of the large leaves before forming a chrysalis. That’s a lot of food!

I love watching them munch through leaves. You can even hear larger caterpillars eating. So, in honor of the ending of another caterpillar season, I present a few short clips of caterpillars chomping on their larval lunches…

 

 

 

 

 

Disguised Beauty

…the repulsive larva, tissue by tissue, is transformed into the superlative beauty of the adult moth. Beauty will come from beauty in disguise.

~Edwin Way Teale, on caterpillar transformation

Monkey Slug tan color

Monkey Slug caterpillar (click photos to enlarge)

This was a good year for some unusual caterpillars. For some reason, while looking for larvae a couple of weeks ago, we managed to find several of one of the strangest larval forms to be found in these parts, the Monkey Slug caterpillar, Phobetron pithecium. As if Monkey Slug wasn’t weird enough, this well-disguised creature also goes by the moniker of Hag Moth larva. You can read more about these cryptic critters in a previous post from last year’s BugFest outing.

Monkey Slug orange color

Monkey Slug larvae can be various shades of color from tan to rust

These guys can be difficult to spot as they tend to look like a piece of dried leaf edge. They are generalist feeders which means you can’t search just a few types of plants for them. It’s more a matter of developing a search image and just plain luck. This year we found them on an elm, a multi-flora rose, and a hickory.

Before returning the larvae to their former haunts, I kept them for a couple of days to observe their behavior. Turns out they fit the family name, Slug Moth caterpillars (Limacodidae), and are quite sluggish in their feeding and movement. Here is a short clip of one feeding when viewed from below.

It reminds me of an odd-shaped, fuzzy mitten trying to gnaw the edge of a leaf. The larva tends to keep its head tucked much of the time.

Monkey Slug from below

Monkey Slug from below

These are listed as one of the “stinging” caterpillars with various references saying they have urticating spines hidden in the “hairs” of the lateral processes (wavy arms), and perhaps elsewhere on their body. I wonder if those whitish tufts visible along the sides, when viewed from below, are also clusters of stinging spines?

This individual was fairly active on its host twig and I managed to twist the twig around to watch its locomotion skills. Another short video clip clearly shows why this group has the word slug in its family name.

While somewhat slow, and definitely bizarre, these caterpillars are one of my favorites. Now, I just need to find an adult moth at my moth light next year.

Blending In

When we see leaf-eating insects green, and bark-feeders mottled grey, the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger.

~Charles Darwin

Yesterday, while working in the yard, I stumbled across an unusual caterpillar just beneath the surface of my mulch pile. Two things about it jumped out at me – first, it was pretty large compared to most caterpillars so early in the year, and second, its colors were so striking. And then, to add another, when I picked it up, it jumped and thrashed from side to side.

Ilia Underwing larva on twig

Ilia Underwing larva (click photos to enlarge)

I remember seeing a picture of this species in my caterpillar bible (Caterpillars of Eastern North America, by David L. Wagner) but this was the first one I have encountered. After identifying it as an Ilia Underwing, Catocala ilia, I discovered it is actually one of the most common of the underwing moth species in the East. How have I missed seeing one all these years? Then I read that there is only one generation per year and mature caterpillars are most often seen in early spring. To be honest, over the years I admit to doing more of my caterpillar searches later in the season, when some of our more showy species reach their full size. Look what I have been missing! Sources say that the eggs are laid in the fall and hatch in early spring. The larvae feed primarily on oak leaves. Perhaps my find was burying down into the mulch getting ready to pupate.

Ilia Underwing larva showing rosy underside

Ilia Underwing larva showing a glimpse of the rosy underside

The dorsal surface can be gray or brown, or, as in this case, a mottled color that is a great mimic of a lichen-covered twig. One thing they have in common is a noticeable rosy color to their ventral surface (this guy did not like to be handled so here is just a glimpse of its rosy underside).

Ilia Underwing larva on lichen 2

Ilia Underwing larva blending with a lichen-covered branch

I brought the larva inside with a couple oi twigs I found laying nearby and photographed it. When I nudged it onto a twig, it would thrash, and then crawl a short distance and assume the position. When on a bare twig, it clings tightly but is visible (perhaps the gray or brownish larva blend in better on bare twigs). But when it crawled onto the lichen-covered branch, I could see how this caterpillar can literally disappear before your eyes (or perhaps those of a hungry bird).

Ilia Underwing larva on lichen close up

The color patterns and textures of this larva are a great lichen mimic

It is always a treat to discover something new and learn how it lives its life just outside my window…all I need to do is get outside and look to once again be in awe.

So Many Green Things, So Little Time…

black swallowtail caterpillar after molt

Black Swallowtail caterpillar after molt (click to enlarge photos)

There has been a spate of caterpillar sightings the past few days, especially of the big green kind. I know this is just to get me overly hopeful that some of them may actually still be around for use at the caterpillar tent this coming Saturday at the NC Museum of Natural Sciences big special event, BugFest ( see http://bugfest.org/ for details). Indeed, the timing of BugFest this year has me worried that many of the cooler cats that have been out and about will decide it is time to pupate a day or two before the event, leaving us with a precious few to entertain and educate the thousands of visitors expected to attend. It has been a great year for Black Swallowtals in the garden, but suddenly, the caterpillars have all but disappeared, as has their food supply of parsley and fennel. I saw one female laying eggs late last week, so I am hopeful a few of them make it, but most are busy feeding and molting their way to pupation in a hurry as the cooler weather sets in.

Luna caterpilar on Persimmon

Luna Moth caterpillar on Persimmon

I was checking a Persimmon tree late last week and was surprised to find this guy, one of my favorite caterpillars, feeding on it. This is the larva of one of the most beautiful moths in our area, the Luna Moth. I usually find them on Sweet Gum so I initially thought this was a Polyphemus Moth caterpillar as my experience has been that species favors a wide variety of tree leaves. But a closer look revealed the tell-tale yellow stripe along the length of the abdomen and the stripes at the trailing edge of each abdominal segment that separates the Luna from the Polyphemus (whose oblique stripes run through the spiracles along the sides).

Tobacco Hornworn on tomato

Tobacco Hornworn on tomato

The final big-green-eating-machine found last week was a Tobacco Hornworm on one of my few remaining tomato plants. This has not been a good year for tomatoes in my garden as the excessive early rains may have encouraged the blight, so there have been relatively few of these common garden caterpillars around. When disturbed, this one pulled into the characteristic posture that gives this family its name—they elevate the front part of their body and assume a posture reminiscent of the Egyptian Sphinx. Unfortunately for me, this one is large enough that it most certainly won’t last until BugFest. But, I will be out and about looking for more (hopefully successfully) the next few days so I hope you will tolerate a few more posts on caterpillars. They are one of my favorite subjects to photograph and I have found them to be one of the best ways to help get people of all ages excited about nature. If you are in Raleigh on Saturday, September 21, be sure to stop by  the caterpillar tent outside the main museum and let us share the excitement with you.

And a late note…I had this prepared to post tonight but went out today looking for caterpillars and had quite a day – more in a future post later this week.

Dressed for Success

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

And there is one species of caterpillar that dresses better than any other – the Camouflaged Looper, Synchlora aerata. This is the unusual larva of the Wavy-lined Emerald Moth (okay, the quote isn’t quite right in this case…).

Camouflage Looper

Can you see the caterpillar?

Every time I am out in the garden I always take a few moments to just look around for interesting critters. As I watched a few pollinators on the Blazing Star (Liatris sp.) yesterday, I noticed something move. But there was nothing there…then it moved again, and I knew what it was – a Camouflaged Looper. This caterpillar has the unusual habit of disguising itself by cutting plant parts from the flowers on which it is feeding and sticking them onto its dorsal surface. The larvae feed on a wide variety of plants although I have most often found them on Blazing Star, Black-eyed Susan, and a few other yellow composite flowers.

Camouflage Looper 3

Camouflage Looper and its “costume”

In a 1979 article in The Journal of the Lepidopterists’ Society, Dr. Miklos Treiber, of the University of North Carolina, wrote about the camouflage abilities of these inchworms. The larvae cut off flower parts, seeds, and even entire flowers, and attach them to needle-like projections on their upper body surface. In a series of experiments he removed their floral covering and they immediately  began to replace the camouflage.

Camouflage Looper on yellow flower 1

Camouflaged Looper on yellow composite

Furthermore, when moved from one flower type to another (purple to yellow in his case) the larvae began to replace their old camouflage with flower fragments from the new plant.

Camouflage Looper 4

Camouflaged Looper on Blazing Star

He also noted that the fragments are passed through the mouth of the larva before being attached and that a mucilaginous substance (aka “caterpillar spit”) was secreted by the larva onto the fragments. He speculated that this substance seems to play a role in maintaining the freshness in these fragments. The caterpillars also maintain the effectiveness of the covering by replacing withered floral parts with fresh ones.

Camouflage Looper 5

Camouflaged Looper looks like plant debris when not on matching flower

Dr. Treibe hypothesized that this looper’s ability to change disguises allows it to have a much more varied diet than some other caterpillars because it isn’t restricted to eating only those flowers or plant parts that it resembles in appearance. And I noticed that even when it is moving between flowers and is on a stem, leaf or other background, the caterpillar simply looks like some plant debris rather than a potentially tasty meal for any passing bird.

Black Swallowtail eggs

Black Swallowtail egg on fennel

Black Swallowtail egg on Bronze Fennel (click to enlarge)

As I was planting some veggies yesterday, I saw a female Black Swallowtail butterfly in her characteristic search and hover mode as she investigated various plants in the garden. I knew from this fluttery flight behavior that she was searching for the right type of plant on which to lay an egg (aka host plant). As with many species of butterflies and moths, Black Swallowtail females tend to be discerning when it comes to which plants they choose for their eggs. Host plants of the caterpillar include members of the parsley family (Apiaceae) including Carrot, Parsley, Dill, Fennel and Queen Anne’s lace and some members of the Rutaceae such as common garden Rue (Ruta graveolens).

I have four of these in the garden right now: Parsley, Bronze Fennel, Sweet Fennel, and Rue. From my experience, the Bronze Fennel seems to be the preferred host, especially early in the season. The tops of the Carrots I grew last year were also very popular with the caterpillars. As any herb gardener knows all too well, Parsley is also immensely popular as a host plant, with the larvae often totally denuding your herb supply if you only have a few plants. That is one reason I plant the fennels as they tend to get tall (3 or 4 feet) which is usually enough to provide an adequate food supply. Rue becomes especially important as a host plant in my garden in the late summer and early fall as Black Swallowtails complete their final generation before winter. Last year I had one large rue plant with over 20 caterpillars on it and rue tends to be less completely devoured compared to some of the other hosts. Rue stems also tend to sprout quickly after being eaten. But I have also read that Rue can cause skin irritation in sensitive people, so be cautious if you plant it.

Bronze Fennel

Bronze Fennel (click to enlarge)

Sweet Fennel

Sweet Fennel (click to enlarge)

Parsley

Parsley (click to enlarge)

Rue

Rue (click to enlarge)

Rue

Close-up of Rue foliage (click to enlarge)

Naturally, I was excited to see what I thought were the first butterfly eggs of the season in the garden. I grabbed my camera and took a few shots after finding eggs on several fennel and parsley plants. The eggs are spherical and cream-colored (or slightly yellowish). The other swallowtail species eggs I have seen are also spherical although different species tend to have different colors. The eggs of other butterfly and moth groups can be quite ornate with many shapes, colors, and ornamentations (perhaps a blog topic later this season). Each butterfly egg is surrounded by a hard outer shell, called the chorion, to protect the developing larva. The shell is lined with a layer of wax, which helps keep the egg from drying out. There is a small opening near one end called a micropyle, which allows sperm to enter the egg for fertilization. The egg shell also is dotted with microscopic pores called aeropyles which allow gas exchange. The butterfly glues the egg to the plant leaf using an adhesive-like substance produced in the colleterial glands. Black Swallowtails lay the eggs singly (generally on the top of leaves) although she may lay several eggs on the same plant.

Black Swallowtail egg on parsley

Black Swallowtail egg on parsley (click to enlarge)

As I wandered the garden looking for more eggs, I realized the one I photographed is not the first of the season…I found a tiny caterpillar on one of the Rue plants. Since it takes 3-5 days for these eggs to hatch, I had apparently missed a few from the past weekend.

First instar Black Swallowtail larva

First instar Black Swallowtail larva (click to enlarge)

This is what is known as the first instar larva, the stage after emergence from the egg. It looks quite different from how this species is pictured in most caterpillar field guides. As is common with many species, Black Swallowtail caterpillars undergo a noticeable change in appearance as they molt five times on their way to becoming a chrysalis. This early stage is considered a bird poop mimic, with a dark background color containing a whitish splotch, just like a bird dropping. Many other species have this basic color scheme, especially as early stage larvae.

Black Swallowtail caterpillar next to pencil point

Black Swallowtail caterpillar next to pencil point (click to enlarge)

I’ll hang onto this little guy and try to photograph it as it develops over the next couple of weeks. I think I’ll have plenty of opportunity to get the various life stages as I found 11 eggs (and two more first instar larvae) on one Bronze Fennel plant this morning.  While searching the Internet for a few details on these eggs, I found what could be my moneymaker in retirement – seem like a few companies sell butterfly eggs for people to raise and I saw one site that had Black Swallowtail eggs for $2 each! If I had the time and inclination, it could be a busy (and profitable) summer.