Application of Dyar's Law to Life Stages ofSigara mathesoni(Heteroptera: Corixidae)

Abstract

Sigara mathesoni, collected from Big Spring Creek in south-central Pennsylvania, were observed under laboratory and field conditions in 2007 in order to test Dyar's law in predicting developmental stage from head width. In the laboratory, eggs were collected with subsequent hatch- ing. Head width was obtained at each developmental stage. It was found that Dyar's law accurately modeled growth of S. mathesoni and instar number is easily determined by head width measurement. In the final two stages of growth, head width and body length were sexually dimorphic. Female head width was larger than male head width.