Studies were made of the behavior ofSennius morosus(Sharp),S. simulans(Schaeffer),S. medialis(Sharp), andS. fallax(Boheman). The behavior of these closely related seed beetles was modified greatly because of the nature of the pods and seeds of their host plants. All five host plants had dehiscent pods. Those plants with many small seeds were attacked before the fruits matured; a beetle larva consumed several seeds and pupated inside the fruit. The plants with larger seeds were attacked at or near maturity; the beetle larva fed and pupated inside one seed. Those species of seed beetles that oviposited on immature, still expanding pods, produced eggs with strands which attached them to the substrate. Presumably these strands are a modification to allow eggs to adhere to an expanding pod.