182 INSECTS AFFECTING VEGETATION 



wheat bulb worm, army worms, cutworms, and various sawflies. 

 Then there follows a great horde of insects of minor importance 

 which need not be considered in this connection. This is leaving out 

 of consideration the locusts, or grasshoppers, including the Rocky 

 Mountain, or migratory species, which occasionally injure wheat, 

 but such injury is unusual and as a rule limited to migrations of 

 locusts from one section to another, which are of infrequent occur- 

 rence nowadays, at least in the principal winter wheat growing re- 

 gions, and have never been noteworthy except in the western districts. 

 (Farmers' Bui. 132.) 



The Chinch Bug. The chinch bug is certainly responsible for 

 as great annual losses to farm crops as any other injurious species of 

 insect known, and it is very improbable that any other species causes 

 anything like the damage which is chargeable to this pest. This is 

 due to its wide distribution, its prevalence more or less every year, 

 the enormous multiplication in favorable seasons, and to the fact that 

 it attacks all the cereals and most forage plants. Much of this loss 

 undoubtedly can be avoided by a proper system of farm management 

 and the adoption of known methods of control. 



The important natural agencies responsible for the abundance 

 or scarcity of this insect are not insect parasites, for it has none of 

 any importance, but unfavorable climatic conditions and the various 

 .diseases induced thereby. The chinch bug is notably an accom- 

 paniment of drought, and very rarely, if ever, is serious injury 

 caused by it in other than dry seasons. Wet weather is very prejudi- 

 cial to it and develops various fungous diseases, which as a rule very 

 promptly result in its practical extermination for the season. 



From the standpoint of control no feature of the life history of 

 this insect is so important as its overwintering habit. The general 

 belief has been that the species hibernates beneath rubbish, such as 

 old straw, or matted grass, or leaves in hedge rows, and this is prob- 

 ably often the case to a certain extent, but undoubtedly the normal 

 place of hibernation is in the dense stools, especially of wild grasses, 

 and also of such cultivated grasses as incline to the stooling habit. 



The chinch bug goes through six different stagas, from the egg 

 to the adult insect. The egg is less than three-tenths of an inch long, 

 cylindrical, and squarely docked at one end, in color pale or whitish 

 when first deposited, but later showing the colors of the developing 

 embryo through the shell. The newly hatched larva is but little 

 larger than the egg and resembles the adult insect in miniature ex- 

 cept in having no wings. It is of a pale reddish color, with a yellow 

 band across the first two abdominal segments. The second larval 

 stage resembles the first except in being larger, and having the head 

 and thoracic segments dusky and hardened. After the second molt 

 there is again an increase in size, and the head and thorax become 

 still darker and more coriaceous. The next molt introduces the 

 pupal stage of the insect, which resembles the adult almost exactly, 

 except that the wings are replaced by mere wing pads, which latter 

 had already been foreshadowed in the last larval stage. The next 



