COMPARATIVE-STUDY OF LIFE-HISTORIES, LABORATORY REARING, AND IMMATURESTAGES OF EUSCHISTUS-SERVUS AND EUSCHISTUS-VARIOLARIUS (HEMIPTERA, PENTATOMIDAE)

A comparative study was conducted of the field life histories of Eusch istus servus and E. variolarius in southern Illinois, their life cycle s under controlled laboratory conditions, and their immature stages. T he results indicate that E. servus is bivoltine and E. variolarius is univoltine. Adults of both species emerged from overwintering sites du ring early April, began feeding and copulating on leaves of common mul lein (Verbascum thapsus) and surrounding vegetation, and reproduced sh ortly thereafter. Neither eggs and first instars of either species, no r second instars of E. variolarius, were collected in the field. Seaso nal occurrences of the adults and subsequent immature stages are discu ssed for each species. No individuals were found after the first week of November. Both species were reared on green beans (Phaseolus vulgar is) under a 16L:8D photoperiod and constant temperature of 23 +/- 0.06 -degrees-C. The incubation period averaged 5.8 days for E. servus and 5.4 days for E. variolarius. Durations of the 5 subsequent stadia aver aged, respectively, 5, 6, 6.7, 9.3, and 11.5 days for E. servus, and 4 .9, 5.7, 7.8, 9.7, and 13.3 days for E. variolarius. Comparisons of in cubation period and stadia between the two species showed that only th e stadia for the first instars were not statistically different. Total developmental period was longer for E. variolarius than for E. servus . The external anatomy of the egg and each of the five nymphal instars is described for each species.