Bagworms are approaching 1/2 inch in length in extreme southern Illinois and points south. Caterpillars this large have ended their dispersal stage—so now is the ideal time to apply insecticidal controls throughout the state before major damage occurs. Larvae this small can be controlled with several insecticides, but Bacillus thuringiensis kurstaki (Dipel, Thuricide), trichlorfon (Dylox), and cyfluthrin (Tempo), as well as other synthetic pyrethroids, will be most effective on these and older larvae.