MONITORING EMERGENCE OF FERAL HELICOVERPA TEA (LEPIDOPTERA, NOCTUIDAE) FROM SENESCENT CORN

We compared various sampling procedures to monitor adult emergence of feral corn earworm, Helicoverpa tea (Boddie), from senescent corn. The three techniques compared were as follows: (1) collection of pupae in 94 fields and holding them in two types of individual emergence cages ; (2) use of large emergence cages located in 12 selected cornfields; and (3) direct observation of nocturnal adult emergence from a plot in a cornfield in which the stalks were removed. Most emergence occurred over a period of approximate to 7 d, but an extended period of emerge nce was observed with all methods. However, the accuracy of measuremen t of this prolonged emergence period is questionable with the pupal sa mpling and nocturnal observation monitoring techniques because these t echniques do not account for the larvae still present in the ears when the pupal samples are collected or when stalks are removed, respectiv ely. Although all three methods indicated that females predominated du ring the early stages of emergence, this phenomenon was more pronounce d in direct nocturnal observations. Pooling of insects from different fields that vary in phenology with pupal sampling and large cage techn iques obscures the emergence pattern from individual fields, but is mo re reflective of the area-wide emergence pattern. Although area-wide e stimates of density of populations of emerging adults are best provide d by pupal sampling because of the large numbers of fields sampled, us e of the large emergence cages in selected fields is an excellent alte rnative limited only by availability of cages. The best technique depe nds on use of the emergence data, available resources, and specific as pects of the situation, with the uniformity of corn phenological devel opment being of critical importance.