We have caterpillars….do we ever have caterpillars. And as with all babies, having caterpillars means dealing with two things: food and poop. The technical term for insect poop is frass, a term that inspired one of our lab volunteers to create a refrigerator magnet design what we enjoy very much.
Frass is happening in a big way at the moment. All three of our fritillary species, the silver-bordered, the Aphrodite, and the regal, have hatched in abunance. We have at least 100 larvae from each species, and have counted over 300 silver-bordered fritillary larvae. They are the easiest to count right now. They hatched first, and they grow the fastest. Caterpillars of all three of these species feed on violets. Fortunately, we have quite a few growing right on the museum grounds, so our food supply isn’t far away. As you can see from the photo, they produce quite a lot of frass at this stage. Their food consumption and growth are amazing. If a human infant were to grow as rapidly as some caterpillars, a four week old baby would be about the size and weight of a school bus.
Silver-bordered fritillary caterpillars
The silver-bordered larvae are currently in the third and fourth instars. Instars are the stages between molts. The first instar hatches from the eggs, begins feeding, and then molts to become the second instar. These caterpillars will all go through five instars before becoming chrysalises. I expect the first pupation to begin next week. I’m particularly excited about having regal fritillary larvae in the lab at the moment. This species is endangered over most of its range east of the Mississippi River. In Illinois, they are a threatened species.
In other endangered species news, the first adult of the highly endangered swamp metalmark caterpillars has emerged from its chrysalis. This is the first swamp metalmark adult that we have ever raised here at the museum. The only species that really isn’t doing well for us at the moment is the purplish copper. They had a terrible year this year. We only managed to find 2 females, and only got a couple of dozen eggs out of them. Only one egg has hatched. This species overwinters in the egg stage, so I believe that the rest of the eggs are simply dormant for winter. We have popped them into the refrigerator and will try to re-animate them after giving them a period of cold storage. The bright spot here is that the one caterpillar that hatched is doing extremely well for us. They appear easy to rear.