DESCRIPTION OF THE PEST, 



The fully developed insect, somewhat resembling a small, winged 

 black ant, is clearly shown, enlarged, in figure 1, its natural size being 

 indicated by a line at the right. The color is black, with joints of legs 

 and feet yellow. The larva or grub is whitish, with brown jaws, the 

 length being about the same as that of the adult, and the form much 

 like that shown in figure 2, which represents the larva of a nearly 

 related species. 



LIFE HISTORY. 



The insect may be found in wheat stems, in its various stages of devel- 

 opment, throughout the year. It lives through the winter as a larva 



or grub in cells formed in the 

 stems prior to the ripening of 

 the grain, the adult emerging 

 therefrom in April or May, ac- 

 cording to 

 latitude, or Mr^ 

 some time 

 after the 

 young grain 

 has thrown 

 up stems 

 and several 

 joints have 

 become ex- 

 posed. The 

 female, us- 

 ing her slen- 

 der, pointed 

 ovipositor, 

 places her 

 ego's in the 

 stems. The 

 exact posi- 

 tion assum- 

 ed is shown 

 in figure 3, 



from a photograpli from Hfe 

 by Mr. G. I. Reeves. The eggs 

 hatch and the young grubs, 

 forming cells, feed in the 

 y.alls of the stem, reacliing their nuixinnuu growth by the time the 

 straw becomes fully hardened and ripe. Wintering in the larval 

 state, they pass a short pupal stage and emerge as adults in the 

 spring. While there are both males and females among these insects, 



ICir. 00] 



Fig. 2.— Jsosoma grande: 

 Larva of the wheat- 

 straw worm; e, anten- 

 na; /, jaw. Line at 

 riglit indicates natural 

 length. (After Riley.) 



Fig. 3. — Female Isosoma in act of depositing egg in 

 stem. About life size (autlior's illustration). 



