The location of first instars within their habitat is largely determined by the oviposition behavior of females, who tend to deposit their eggs near resources. Female Peri-
planeta brunnea, for example, generally glue their oothe-cae near a food supply (at least they do in 1 gal battery jars) (Edmunds, 1957).There is some evidence to suggest, however, that, like locusts (Lauga and Hatté, 1977; Loher, 1990), some cockroaches may employ oviposition pheromones. These serve to either convene gravid females in certain locations for egg laying, or attract them to sites where conspecifics have previously deposited oothecae. Edmunds (1952) found 184 oothecae of Parcoblatta sp. deposited in close proximity under tree bark. Similarly, oothecae of Supella longipalpa were found in clusters by Benson and Huber (1989). The authors observed ovipositing females deposit a drop of "genital fluid" on oothecae, and suggested that it contains a pheromone that attracts other females. Gravid females of B. germanica generally do not leave the harborage (Cochran, 1983b); consequently, first instars hatch into an aggregation (Rivault, 1989; Koehler et al., 1994). Stray females, however, may actively seek aggregations for oviposition. Escaped females of B. germanica in laboratory colonies laid their oothecae near a group of conspecific nymphs (Ledoux, 1945).
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