Comparative Anatomy and Histology of Selected Systems in Larval and Adult Phyllophaga anxia (Coleoptera: Scarabaeidae)1

Abstract

The anatomy and histology of digestive, nervous, respiratory, and reproductive systems in 3rd-stage (full grown) larvae of Phyllophaga anxia (LeConte) are compared with the same systems of adults. Despite what appear to be major anatomical differences, a study of microanatomy has revealed that the digestive systems of larvae and adults are quite similar. The nervous systems of larvae and adults are characterized by concentration of all ganglia of the ventral nerve cord in the pro- and mesothoracic segments. Metameric nodes are present in the tracheal trunks of larvae, but not in those of adults. Many air sacs, which are not present in larvae, are associated with trachaea of adults. Primordial gonadal tissues are present in 3rd-stage larvae; however, meiosis does not begin until the pupal stadium. Adults do not become sexually mature until they are about 10 months old, at which time they leave the soil, after overwintering, then mate and oviposit.