Note on Oviposition in Plant Stems by Grasshoppers (Orthoptera: Acrididae)

Extract

Most species of grasshoppers in North America appear to lay their eggs in soil or among grass roots. A variation of this habit was reported in Manitoba by Criddle (1933) who states that Chloealtis conspersa Harr. and Neopodismopsis abdominalis (Thom.) oviposit exclusively in decaying wood or in dung.

Recently, a few stems of sweet clover, Melilotus alba Desv., and Russian thistle, Salsola kali L. var. tenuifolia Tausch, that contained insect eggs, were sent to the Saskatoon Research Station by A. Vadeboncoeur of Val Marie in southwestern Saskatchewan. These eggs were laid in the pithy centres of the stems in groups of eight or nine (Fig. 1). According to the sender, the clover had been cut during the summer and the thistle was about two years old. Both were lying in the ditch on the railroad right-of-way. At our request, Mr. Vadeboncoeur sent in a few more infested stems. From a total of about 10 samples it seems evident that oviposition in plant stems is typical of the grasshopper involved. The exact egg-laying procedure is difficult to visualize in view of the small diameter of the pith (approximately 3 mm.), and the lack of any sign of penetration through the side of the stem. Inserting its abdomen into the narrow stem and depositing the eggs 25 to 30 mm. from the cut end of the stem must have involved considerable gymnastic manoeuvring by the female grasshopper.