442 INSECTS INJURIOUS TO VEGETATION. 



becomes hard. They do not burrow within the kernels, but live 

 on the pollen and on the soft matter of the grain, which they 

 probably extract from the base of the germs. It appears, from 

 various statements, that very early and very late wheat escape 

 with comparatively little injury ; the amount of which, in other 

 cases, depends upon the condition of the grain at the time when 

 the maggots are hatched. When the maggots begin their depre- 

 dations soon after the blossoming of the grain, they do the greatest 

 injury ; for the kernels never fill out at all. Pinched or partly 

 filled kernels are the consequence of their attacks when the grain 

 is more advanced. The hulls of the impoverished kernels will 

 always be found split open on the convex side, so as to expose 

 the embryo. This is caused by the drying and shrinking of the 

 hull, after a portion of the contents thereof has been sucked out 

 by the maggots. Towards the end of July and in the beginning 

 of August the full-grown maggots leave off eating and become 

 sluggish and torpid, preparatory to moulting their skins. This 

 process, which has been alluded to by Judge Buel and some other 

 writers, has been carefully observed by Mrs. Gage, who has sent 

 to me the maggots before and after moulting, together with some 

 of their cast skins. It takes place in the following manner. The 

 body of the maggot gradually shrinks in length within its skin, and 

 becomes more flattened and less pointed, as may easily be seen 

 through the delicate transparent skin, which retains nearly its 

 original form and dimensions, and extends a little beyond the in- 

 cluded insect at each end. The torpid state lasts only a few 

 days, after which the insect casts off its skin, leaving the latter 

 entire, except a little rent in one end of it. This cast skin is 

 exceedingly thin, and colorless, and, through a microscope, is 

 seen to be marked with eleven transverse lines. After shedding 

 its skin, the maggot recovers its activity, and writhes about as at 

 first, but takes no food. It is shorter, somewhat flattened, and 

 more obtuse than before, and is of a deeper yellow color, with an 

 oblong greenish spot in the middle of the body. Within two or 

 three days after moulting, the maggots either drop of their own 

 accord, or are shaken out of the ears by the wind, and fall to the 

 ground. They do not let themselves down by threads, for they 

 are not able to spin. Nearly all of them disappear before the 



