274 



STATE ROAP.T) OF AOnTrULTTTRE. 



less advanced than those bearing the galls in the middle part or in the 

 upper part. When the eggs hatch into larvae, their effect is soon notice- 

 able in the thickened wall of the culm or straw proper. This thickening 

 becomes apparent both by the increase in cHametor and by tlic diminish- 

 ing size of the bore in the straw, the central canal sometimes becoming 

 completely closed. At this time, slicing the straw reveals cavities in 

 the walls in which cavities are to be seen the gi-u])S or larvae. The straw 

 also becomes woody and often distorted so that in some fields one finds 

 bent and twisted straws which refuse to stand erect, but he on the ground 

 instead, where they escape the reaper even if the heads succeed in filling. 

 '^I'he straws that are attacked seldom produce their full weight of grain, 

 although the loss varies from a slight slu-iidvagc to almost a total absence 

 of seecl. 



At threshing time the woody sections are apt to break out in the 

 separator, resulting in a lot of peg-like hard fragments from half an 

 inch to three inches in length, and often this is the first intimation to 

 the farmer that anything is wrong. Fortunately, few of the larvae in 

 these woody sections live through the rough treatment that they re- 

 ceive during threshing, as repeated trials have shown us, since we have 

 never succeeded in rearing any adults from such material. 



The stubble from the same fields, on the contrary, usually yields 

 quantities of adults when placed in beeeding cages, and in the stubble 

 lies the danger, since it is here that the little fellows winter over. If 

 our sj^stem of agriculture permitted the deep plowing of wheat stubble 



immediately after harvest, the trouble with joint- 

 worm and several other troublesome pests would 

 largely disappear. Our custom of using wheat 

 for a nurse crop for clover prevents us from 

 settling the matter in this way. There are left 

 to us the employmc^nt of measui'cs unfavorable 

 to the insects and the substitution for a year or 

 so of a grain crop immune to the joint-worm. 

 The crop that comes most nearly up to our 

 ideas of a substitute is rye, although rye is 

 sometimes dightly attacked by the wheat joint- 

 worm. Barley is often badly attacked and so 

 far as Michigan is concerned, no other grain crop 

 would l)e seriously and generally considered. 



It must be remembered when considering 

 practices unfavorable to the pests that the 

 adult insects, when borne on favoi'able winds, 

 fly the better part of a mile and it would be 

 hopeless to even try to put new wheat fields 

 at a distance of half that distance from old 

 stubble. Nevertheless, it is well to avoid sowing 

 new wheat any nearer old stubble than is necessarj^ during an outbreak. 

 Since the insects winter over in stubble and comparatively few sur- 

 vive thcwjourney through the separator, it follows that the shorter the 

 stubble the fewer the pests that will winter there. Therefore, cut low. 

 Some groovers prefer to cut high and then after the old dead straws have 

 rotted someVhat at their bases, to comb out the dead straws with a 

 side dehvcry rake and destroy by fire. In no case should wheat follow 

 wheat during an outbreak. 



WHioat ,T o i n t - w () r m.— 

 { I siisiitiKi Irilici) i'upa from 

 (•avity in straw, enlarged 

 (original). 



