Larval Leftovers

Every September, for as long as I can remember (or at least well more than a decade), I have been collecting caterpillars in preparation for the annual BugFest event at the North Carolina Museum of Natural Sciences. It is always great fun to share these larval lovelies with the thousands of visitors that make the pilgrimage to this super annual event. But, there is a price to pay – the care and feeding, and eventual release, of all the stars. And so it was, again this year. Given the timing of the event in mid to late September, it is always touch and go as to whether we will find enough caterpillars or if the ones we do find will actually make it to the big day without pupating. So, here are a few brief stories of some of this year’s stars, or almost stars, as the case may be.

Stinging Rose Caterpillar 1

Stinging Rose Caterpillar (click photos to enlarge)

I was very happy when I found this unusual beauty, a Stinging Rose Caterpillar (Parasa indetermina) on a willow, the week before BugFest. These odd-shaped and brightly colored larvae are one of the stinging caterpillars, and this one was sure to be a crowd-pleaser. But, as is often the case when dealing with nature, it was not to be.

Stinging Rose Caterpillar with parasite cocoons

Parasitic wasp cocoons on the Stinging Rose Caterpillar

A few days before the big event, it succumbed to a common caterpillar threat, the emergence of parasitic wasp larvae that quickly spun cocoons, coating the caterpillar’s body with what look like tiny cotton swab tips. I was going to take it anyway, to share that unusual aspect of the ecology of life as a larva, but, the day before the event, the caterpillar shriveled up to nothing, cutting short this one’s chance at fame. These parasites are fairly common and I always find a few caterpillars that already have the cocoons present when I am out collecting. But it is particularly disappointing when you collect something unique, only to find out later that the parasitic larvae were already at work, but you just could not tell until they popped out in a moment reminiscent of the classic scene from the movie Alien.

Spiny Oakworm shedding

Spiny Oakworm shedding its skin

In what looks like another scene from a space aliens movie, I was witness to one of the miracles of the caterpillar world when one of my captives managed to molt under my care. This one, a Spiny Oakworm (Anisota stigma), was still for almost two days and I suspected it was undergoing changes related to either molting or pupation. Right before packing up for the event, I saw this change-of-clothes act. Note the dramatic difference in color between the freshly molted larva and its cast skin. The caterpillar gradually darkened just in time to share its new look with the crowds.

Puss Caterpilar underside

Underside of Puss Caterpillar

I already posted on my experience with one of the most notorious of the stinging caterpillars, the Puss Caterpillar. When I was transporting it for release (my goal is to release these critters back into the general area where they were collected each year) I placed it in a plastic container like the ones you buy fresh salad in at the grocery store. When the larva crawled around the clear sides it provided me with a great view of the underside of this furry beast, something you don’t normally get to see.

Monarch larva chewing leaf

Monarch caterpillar chewing milkweed leaf

A friend loaned me a couple of large Monarch Butterfly larvae, and this one was busy all during the event chewing the edges of a Common Milkweed leaf. I grabbed a moment during the busy day to get a portrait of the feeder in action.

Spiny Oak-Slug top view

Spiny Oak-Slug during the event

Several of the stars started to wander off their food plants during the event. This is usually a sign that their time as a caterpillar is coming to an end and a pupa is on the way. Most larvae go through what I call a “walk-about” stage for several hours before starting to pupate. If they are not contained, they will wander off to some suitable spot and undergo yet another miraculous change in their extraordinary life cycle. And so it was with one of the small beauties of this year’s event, a Spiny Oak-Slug.

Spiny Oak-Slug cocoon

Spiny Oak-Slug cocoon

But, at least it waited until after the event to complete the change from dazzling caterpillar to drab cocoon. It should overwinter in this state and emerge next spring.

Luna Moth caterpillar

Luna Moth caterpillar

I found several large Luna Moth caterpillars the week of the event, and, as usual, a few pupated before the big day. And a couple decided to start the big change during the event itself and had to be confined to caterpillar detention (aka the pupation cage).

Luna Moth larva changing color prior to pupation

Luna Moth larva changing color prior to pupating

Like many species, Luna larvae undergo a noticeable color change right before they start spinning a cocoon, in this case, changing from brilliant green to a pinkish-brown color.

Spicebush Swallowtail nearing pupation

Spicebush Swallowtail in walk-about phase

Another color changer is one of my favorite caterpillars, the Spicebush Swalllowtail. They, too, are bright green, along with their uncanny false eye-spots and other markings. When they start the walk-about phase, they gradually change to a more yellow-orange base color.

Spicebush Swallowtail nearing pupation 1

Spicebush Swallowtai

You can see why these guys are one of my favorites.

Spicebush Swallowtail prepupa

Spicebush Swallowtail prepupa

Once they find a suitable site, they begin laying down their two silk attachment points to form a prepupa. That usually lasts about a day, and then they shed their skin one last time, and, voila, a chrysalis appears.

It is always a bittersweet time when BugFest is over and I release all my specimens. I know the chills of winter will soon be upon us and it will be several months before I can once again observe and photograph one of nature’s most amazing life forms.





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 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.