An allometric study was conducted on the boxelder bug, Boisea trivittata, to confirm the number ofinstars and to identify characteristics most useful for rapid instar identification of field samples. Analysis of field populations collected throughout the 1990-92 seasons indicated that there were five instars, clearly defined on the basis of size and the presence of wing pads. This finding is in contrast with the only other published study on stages of the boxelder bug, which claims there are six nymphal instars.
Size data gathered from field populations were substantiated by laboratory growth studies. Head width and/or second antennal segment length were identified as the most useful parameters for instar identification.
Bouldrey, Scott M. and Grimnes, Karin A.
"An Allometric Study of the Boxelder Bug, Boisea Trivittata (Heteroptera: Rhopalidae),"
The Great Lakes Entomologist, vol 28
Available at: https://scholar.valpo.edu/tgle/vol28/iss3/3