10 BULLETIN 834, U. S. DEPARTMENT OF AGRICULTURE. 



The eggs are inserted in a slit made by the female in the stem 

 some distance above the ground. The young larvae burrow down- 

 ward through the pith of the stem, hollowing it out to the base. 

 The larvae apparently attain full growth at about the time the 

 grain is ripe. At the time the writer's investigations were begun, 

 July 22, they were full grown and had evidently gone into hiber- 

 nation. The fully-developed larvae were, at this time, located at 

 the extreme base of the stem, encased in a silken tube or lining 

 to the burrow, this tube being two or three times the length of 

 the larva and filling the hollow straw completely from about the 

 surface of the ground downward. Above this silken tube the bur- 

 row is completely closed by a wad of frass. Before this wad of 

 frass is put in place the larva almost completely severs the stem 

 from the inside, this cut in nearly every case being at or very 

 near the surface of the ground and usually a little above the 

 first node on the stem where the surface roots put out. In making 

 this cut just enough of the epidermis of the straw is left unsevered 

 to attach it lightly and allow it to stand erect. In consequence of 

 this cut the first slight bending of the ripened straw, as by a strong 

 wind, causes it to snap off and fall. 



Straws cut off by the insect are easily distinguishable from those 

 severed by the harvester. The cut is exactly transverse to the stem 

 and the ends of both the stub which remains in the ground and the 

 fallen straw are distinctly concave or funnel-shaped. This appear- 

 ance is so characteristic that one can readily detect the presence of 

 the pest in a field by simply examining the ends of the fallen straws. 



The hibernating larva, as already stated, is to be found in the 

 stub of the wheat stalk remaining in the ground. Since this stub in 

 most cases barely extends to the surface of the soil (sometimes a 

 little above the surface) , it is not always an easy matter to locate it. 

 The fallen straws sometimes remain slightly attached on one side to 

 the stub, and in such instances one can locate the infested stub by 

 following the straw to its base. When the straw is completely de- 

 tached, as is usually the case in a field that has been harvested, it is 

 often necessary to search for some time before the stub containing the 

 larva can be located. 



The greater part of the insect's life cycle is apparently spent as a 

 hibernating larva, this period extending from about the time the 

 wheat is ripe enough to cut until some time the following spring 

 when the larva changes to the pupa. Just when this change takes 

 place has not been ascertained, but the pupal state is probably of 

 short duration, as in Cephus cinctm; if so, the change to the pupa 

 probably occurs in the latter part of April or early part of May. 

 Adults, as already stated, are to be found in the fields during the 

 latter half of May and early June. 





