VALUE OF A KNOWLEDGE OF ENTOMOLOGY 



parts are for biting. To the Diptera belong such pernicious 

 insects as mosquitoes, house and horse flies, and root-maggots. 

 For illustrations of the Diptera, see figures lo and 20. 

 Orthoptera (Grasshoppers, crickets, roaches, katydids, etc.). 

 — In this order the insects have two pairs of wings, — the first 

 somewhat horny and overlapping when at rest, the second 

 pair thin and folded when at rest in plaits like a fan. The 

 metamorphosis is incomplete, and all forms of the insect (ex- 

 cept the Qgg) are active, with biting mouth-parts. The Rocky 

 Mountain locust is an example of this order (figs. 11 and 12). 

 Hemiptera. — This order divides into three suborders, — the 

 Heteroptera or true bugs, the Homoptera containing aphides, 

 leafhoppers, etc., and the Physopoda or thrips. These groups 



have in common four wings, 

 the mouth-parts in all stages 

 formed for sucking, with in- 

 complete metamorphoses. 



Fig. H . — Rocky Mountain locust 

 (Melanoplus spretus). a. a. Newly- 

 hatched nymph; ii, full-grown nymph; 

 c, pupa, natural size. (After Riley.) 



Fig. 1 2.— Rocky Mountain locust (.Melan- 

 oplus spretus). Adult. Natural size. 

 (After Riley.) 



Suborder Heteroptera. — In the true bugs the anterior wings 

 are thickened at the base and thinner at the extremities and 

 overlap on the back, and the beak arises from the anterior 

 portion of the head. It includes various forms of noxious 

 insects, such as the chinch bug, numerous plant-bugs, (fig. 13), 

 squash bug, and certain beneficial species, such as soldier-bugs. 



Suborder Homoptera.— In this group the wings are of uni- 

 form thickness and usually slope at the sides of the body, the 

 beak arising from the hinder portion of the lower side of the 

 head. In this suborder most injurious pests are found in the 

 aphides (fig. 14), leaf-hoppers and the like. 



