76 NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—I9Q22 
writer made tests to find if insects other than the potato beetle could 
not be used as food for rearing the bugs. Among the insects that 
were tried as food were larvae of Calligrapha from willow, the army 
worm (Cirphis unipuncta Haw.), and Melanoplus femur-rubrum. In 
these tests it was found that the young nymphs of bioculatus failed to 
feed readily on the insects provided. Upon finding that the bugs 
would not feed on the larvae of Calligrapha, a genus of beetles closely 
related to Leptinotarsa, the idea of substituting food: was given up. 
During the present year, 1923, while collecting on the high prairie 
at Fort Snelling, Minn., the writer found both P. bioculatus and P. 
circumcinctus feeding on the goldenrod beetle (Trirhabda canadensis 
Kirby). Only one adult bioculatus was found in the field feeding on 
this beetle, but three nymphs were collected and reared along with a 
dozen nymphs of P. circumcinctus, all of which fed entirely upon 
T. canadensis. Specimens of the goldenrod beetle were then placed 
in jars with fifth-stage nymphs of P. bioculatus which had previously 
fed only upon potato beetle grubs, and several bugs fed upon ihe 
beetles provided. In the writer’s experience only two insects, the 
potato beetle and 7. canadensis, have been observed in nature to serve 
as food for Perillus bioculatus. Altho this Pentatomid has been found 
to feed on certain Lepidopterous larvae, such choice of food appears 
to be unusual for the species. 
Technical Descriptions 
The egg. The eggs are keg-shaped, but rounded off above and 
below, an average egg being 1.2 mm. high and 0.88 mm. at its greatest 
diameter. The upper portion of the barrel is distinctly marked with 
irregular reticulations but these become invisible as the lines approach 
the middle of the egg. The dorsal portion of the egg is encircled by 
a row of semi-erect chorial processes, clubbed at their apices and bent 
inward toward the micropyle. Within this ring is a smaller one sur- 
mounting the top of the egg, a circular carina of nodular structure, 
SS: 
which on its outer circumference has a few supporting ridges that 
radiate from it. (Plate I.) The chorial processes vary slightly in 
number, and of several eggs examined, the number varied from 13 
to 15. The color of a normal egg is deep black, but at times fertile 
eggs may be found which are dark brown to blackish. Infertile eggs 
are invariably pale, altho one pale egg mass was observed in which 
several of the eggs hatched. 
Nymphal instars. The immature stages are represented by five 
nymphal instars, and upon molting for the fifth time the adult stage 
