50 



CEREAL AND EOEAGE INSECTS. 



•OVIPOSITION. 



The process of oviposition, as carried on immediately after emer- 

 gence and copulation, is short and rapid. The females crawl 

 carefully over a head for a few seconds until they find a spikelet 

 which presents the best adaptabilities for egg laying. Oviposition 

 begins before the flowers appear and continues as long as the glumes 

 remain flexible, probably from five to seven days. When the female 

 has selected the spikelet she takes up a position upon the apex, her 

 abdomen elevated slightly above the tip, and immediately extends 



Fig. 27.— Sorghum heads, showing four successive stages in the opening of the sheath or "boot." a 



(Original.) 



her ovipositor, pushing it within the spikelet until it is fully extended; 

 then, with a rapid pistonlike motion, she places the egg. It is 

 doubtful if more than one egg is deposited at a time by a single 

 female in a given spikelet. Dissections of glumes observed to have 

 been oviposited in by but one female, and but once, have not, during 

 the writer's investigations, revealed more than one egg. 



However, it is no uncommon sight to observe several females follow 

 one another in quick succession, ovipositing within the same spikelet. 

 Numerous examinations of infested spikelets have revealed as many as 



a See footnote, p. 51. 



