The topical (LD)_<-50's> represented by μg per insect of several insecticides to brown cockroach, Periplaneta brunnea Burmeister (♀) were as follows : tech.-DDT, 323.593; lindane, 34.277; dieldrin, 6.761; diazinon, 14.454; DDVP, 5.888; malathion, 18.837.
