Using the house fly, Musca domestica L.. as an indicator, numerous triphenyl tin derivatives were found to act as reproduction inhibitors. The more active compounds such as Dowco 186 (triphenyl tin hydroxide), Dowco 187 (allyl triphenyl tin), and Dowco 188 (bis (triphenyl tin) sulfide) have 3 phenyl groups in common, plus a fairly labile fourth group attached to tin. These compounds sterilize adult flies well below the lethal concentration. Females are sterilized at lower concentrations than males. Some derivatives produce easily reversible reproduction control; some do not. This property is somewhat dosage dependent in the house fly with all gradations ranging from nearly complete ovarian suppression to depotition of normal sized but sterile eggs. Triphenyl tins suppress or control reproduction in the German cockroach Blatella germanica (L.), and the confused flour beetle, Tribolium confusum Jacquelin du Val. The triphenyl in moiety would appear to have promise for the reproduction control of insects and related species from several orders of arthropods.