http://www.pet-informed-veterinary-advi ... ntrol.html
I searched on the word "soluble". That is what you want to know, does this wash off with water.
"Invertebrates and selamectin insecticide:
Selamectin and the other macrocyclic lactones are not particularly selective when it comes to insects and, just as they kill fleas and ticks, so too will they also kill a wide range of pest and beneficial terrestrial and aquatic insect species. These chemicals will kill crop, orchard and garden pests like beetles, aphids, mites and certain worms, but so too will they kill insects that are of benefit to gardens, crops, soil and water courses, including: dung beetles, bees and parasitoid wasps. For this reason, such chemicals are rated as being "very toxic to terrestrial environments" and "very toxic to soil environments." Additionally, such chemicals, being water insoluble (hard to flush away), are thought to bind tightly to soil and sediment and to thus persist in the environment for long periods of time, potentially exerting an accumulative, long-term toxic effect on the environment."
Cats roam all over the place and brush up against things. You'd have to raise in a room not visited by your cats and put on clean gloves when working with your caterpillars. I buy boxes of plastic gloves at Costco for working in the garden.