_Natural host._--_Eurycotis floridana_, U.S.A., Florida (Roth and Willis, 1954a). _Experimental hosts._--_Blatta orientalis_, _Eurycotis floridana_, and _Periplaneta americana_, U.S.A. (Roth and Willis, 1954a). _Adult behavior._--Female wasps are sexually receptive almost immediately on leaving the oötheca. Mating takes 3-4 seconds. Males mate repeatedly and may fertilize several females; females may also mate more than once. At about 80° F. the female wasps lived 2-4 days, males one day. _Oviposition._--The female wasp first probes the oötheca with her sheathed ovipositor until she finds an acceptable spot; she then drills through the wall of the oötheca with her ovipositor. One female oviposited for 5 hours, but briefer periods were more usual. We have seen six or more females ovipositing simultaneously into an oötheca of _Eurycotis floridana_. One female was seen to feed on material that oozed from the oviposition puncture. The wasp (pl. 34, A) may oviposit into the oötheca of _E. floridana_ while it is still being carried by the female, as well as in oöthecae that have been dropped and which have hard walls. Eggs 36 days old were successfully parasitized. _Development._--In _Eurycotis floridana_: In the laboratory, development was completed in 34-36 days at about 85° F. This time was regulated to some extent by the number of parasites in the oötheca. There is evidence that larvae eat unhatched wasp eggs or other larvae. In 34 oöthecae exposed to many female wasps, the maximum number of parasites to emerge was 306; yet an average of 601 wasp larvae were dissected from four oöthecae that had each been exposed to 50 female wasps one week earlier. The larvae usually eat all the host eggs. Cockroach eggs that were not eaten by the wasp larvae sometimes developed but usually failed to hatch. Adult wasps made one to six emergence holes in the oötheca; the average number in 42 oöthecae was two holes. _Number of parasites per oötheca._--In _Blatta orientalis_: One of 111 oöthecae exposed to female wasps yielded 48 parasites. In _Eurycotis floridana_: One oötheca parasitized in the field yielded 68 parasites; 8 oöthecae exposed to single wasps for their entire lifespan yielded an average of 50 ± 6 parasites (range 23-81); 34 oöthecae exposed to many wasps for their entire lifespan yielded an average of 198 ± 8 parasites (range 93-306). In _Periplaneta americana_: Nine oöthecae of 152 exposed to the wasps were found to be parasitized when dissected; 11 adults emerged from one oötheca; no parasites emerged from the other 8 oöthecae. _Sex ratio._--4 [F][F]:1 [M] from ovipositions by isolated females. In the one oötheca collected in the field, the ratio was 21.6 [F][F]:1 [M]. Parthenogenesis exists; the unfertilized eggs produced only males. =Anastatus tenuipes= Bolívar y Pieltain