You know you’re an entomologist when…
I was out watering plants and looking at my flowers when I finally found the culprits to an insect crime I’d been watching for for a couple weeks. On my deep red snapdragons, were three caterpillars. I’d been trying to collect seeds from the snapdragon to replant next year. But many of the seed pods had holes in the sides and no seeds. I caught these little guys in the act. And you know you are an entomologist when instead of pulling them off and squishing them, I brought out the camera.
As far as I can tell, these are tobacco budworms Heliothis virescens (also called geranium or petunia budworms). While they are a problem caterpillar that is actually resistant to most insecticides used in gardens, I think they are fairly pretty. But really, they are very damaging. To feed, they chew into the buds and eat the developing flower.
In the picture on the right you can see two holes in buds in the background and see the budworm with its head completely in the third hole it has chewed. Sometimes flowers can survive this and produce flowers full of holes. Mostly, however, this kills the flowers.
In Colorado, Heliothis virescens can survive the winter by pupating in the soil. And their numbers can build up to problem levels. The most common hosts are petunia and nicotiana, but they do attack roses and snapdragons as well. The most effective organic control is hand removal so it’s best to keep an eye out for these guys. The adults are medium sized, light colored moths. I’ll add a picture when I get one from the caterpillar I’m keeping (another sure sign of being an entomologists).
Just a last fun caterpillar ecology picture. When the caterpillars are eating the actual flowers, their poop is purple! (Technically entomologists call caterpillar poop frass). Deep purple frass.