It’s that time of year again when caterpillars seem to be everywhere. Oh sure, caterpillars can be seen from spring till late fall, sometimes in huge numbers. How can you forget those cankerworms that dangled on silky threads from every tree branch by the thousands, no millions, last April.
No, what I’m talking about is the huge variety of species that can be viewed at this time of year. Both moth and butterfly species have been busy all summer producing young and those young are now feeding heavily. Many are beginning to head off to various places to pupate. They leave a trail of frass under the trees and bushes that they feed on, and often the caterpillars themselves can be seen hurriedly crawling across paths, sidewalks, and roads seeking out suitable locations to pupate.
Here’s a small sample of some of the lepidopteran larvae I’ve come across this past week or so.
Banded tussock moths are familiar to most people, although they may not have known exactly what they were looking at when they encountered them. It’s difficult for me to get through the fall without coming across several of these tussock-laced moth caterpillars. Whether dangling from a tree branch by a silken thread or hoofing it across a path, I’m sure to encounter a few of these each fall. They’re not fussy about what species of tree or shrub they feed on. And, they’re widespread. You can find them from Canada to Florida and west to Texas. The caterpillar will eventually become a small brownish moth.
Another nondescript brown moth (there are lots of them) produces a green, nearly hairless caterpillar with white spots and longitudinal lines on its sides and dorsum, the cabbage looper. These moths seem to prefer our food crops to feed upon, but I found one on groundsel tree here in Explore the Wild.
The next species on the list is a butterfly, a cloudless sulphur. Cloudless suphurs are large yellow-green butterflies that prefer to lay their eggs on cassia or senna. Here at the Museum they favor partridge pea. The butterflies are hard to miss as they flutter about the plant laying eggs on the leaves and stems of the legume. Follow a butterfly as it flutters through the air. Watch it land on the plant and reach forward to touch the tip of its abdomen to a stem or leaf. You just witnessed it lay an egg. Go over to the plant and take a close look, you should be able to find the tiny white egg.
In about ten day’s time there should be caterpillars munching on the plant. The larvae may be green or yellow. They’re not always easy to see, but keep looking, you’ll find a few.
Obviously, the caterpillars start out very small (note the egg size). However, they grow quickly and in a another week and a half they will be ready to pupate. Check the plant frequently so as not to miss any of the action.
Occasionally you may be lucky enough to find one of their chrysalids, but don’t be too disappointed if you don’t. They can be difficult to locate.
Partridge pea is common in our area, and it’s native, so don’t feel guilty about planting it in your yard if you so desire. The yellow flowers attract many other species of insect for their nectar. And, it’s visually quite attractive. Can’t beat that.
Some species can be located by finding frass on the ground beneath the tree that they’re feeding on. Frass is what lepidopterists call caterpillar poop. If you see it on the ground, on the pavement or on a bare patch of earth, look up, you’ll probably see a few eaten leaves and hopefully the caterpillars that have eaten those leaves. By the way, keep you mouth closed as you look up. If there are active feeders above they will most likely be disposing of waste.
There are many moth species whose larvae feed in large groups. Two of those active right now are yellow-necked datana and green-striped mapleworm.
The yellow-necked datanas in the following photos were located through the presence of scat on the ground below where they were feeding. They, as mentioned, feed gregariously on various tree species. I found them here on both oak and birch.
The green-striped maple worms were also found by their frass spread out below them as they fed on, you guessed it, maple, red maple to be specific.
Fall webworms are perhaps the easiest caterpillar to locate at this time of year. They build protective webs around the leaves they’re consuming at the time. Their frass is usually caught up in the webs.
Adults are moths. They vary from all white to white with dark spots on their wings. The occurrence of spots seems more common in the south.
A very colorful individual that I recently encountered on the path through Explore the Wild here at the Museum, was a questionmark. No, not the punctuation mark, but a questionmark butterfly larva. It had spikes and spines covering it’s brightly colored head and body.
The butterflies are named for small white markings on their hindwings which suggests a “question mark.”
I’ve come across a half dozen or more snowberry clearwing caterpillars in the past week. All had been marching off across the path in search of safe locations to pupate. The caterpillars feed on honeysuckle, both the native and invasive kinds, and dogbane. We have all of those plants here on the campus so it’s no surprise we have the moths. You’ve probably seen the adult moth feeding on various flowers and thought they were hummingbirds. They’re diurnal moths and buzz around gardens much like hummers do.
That’s just a small sampling of what you might find out-of-doors at this time of year. I suggest taking a leisurely hike around the Museum. Stroll around through our outdoor exhibits to see what you can find. I can almost guarantee, no, I do guarantee, you’ll see at least one species of caterpillar, probably more!