Laboratory studies were made on the biology of the brown-banded cockroach, Supella supellectilium (Serville), and its relative susceptibility to the insecticides, aldrin, chlordane, DDT, heptachlor, and lindane. Biological studies revealed the average preoviposition period for 19 adult females was 17.7 days. An average of 10 egg capsules were produced per female, while the period between capsules averaged 9.8 days. As many as 29 capsules were deposited by a single female, and about one-third from each female hatched. The incubation period of 14 capsules obtained from seven different females averaged 58.4 days. The maximum number of nymphs to hatch per capsule was 18, with an average of 12.8 for all capsules considered. The average length of adult life of 20 females was 115 days. The number and duration of instars were determined by labeling the nymphs with aluminum paint. The total number of instars of 37 nymphs varied from seven to nine, with seven being most commonly found. Significant variation in the duration of instar periods was shown in nymphs from three different females. The total period of nymphal development of 37 nymphs averaged 89.7 days. Toxicity tests were performed on female cockroaches selected immediately after they had emerged as adults. The insecticides were applied topically as emulsions between the prothoracic coxae. The results from these tests show that the brown-banded species does not differ greatly in susceptibility from the German cockroach ( Blattella germanica (L.)) and that the compounds tested can be arranged in the following descending order of toxicity, based on LD50 and LD90 values: lindane, heptachlor, aldrin, chlordane, and DDT.