ROSS: HOW TO COLLECT AND PRESERVE INSECTS 



39 



Sexual characters, and in some forms 

 wings, gradually develop as the insects 

 approach the adult stage, when develop- 

 ment is complete. 



Fig. 34. — Hemiptera. 

 Aspidiotus perniciosus, 

 the destructive San Jose 

 scale. Note "scale" cut 

 away on upper speci- 

 men to show insect 

 proper beneath. Diame- 

 ter less than 0.1 inch. 



Fig. 35. — Hemiptera. 

 Empoasca fabae, the po- 

 tato leafhopper. Actual 

 length about 0.1 inch. 

 This species is pale 

 green. Some species are 

 distinguished by bright 

 red or yellow markings. 



This suborder includes a large number of economic pests, such 

 as the aphids, scale insects, and leafhoppers. Many aphids have 

 a pair of tubular structures near the end of the body ; these are 

 called cornicles and can be seen in fig. 33, of the corn root aphid, 

 Aphis maidi-radicis Forbes. Scale insects usually form a tough 

 scale to cover and protect the delicate body of the insect, as shown 

 in fig. 34 of the destructive San Jose scale, Aspidiotus perniciosus 

 Comstock. Leafhoppers of many kinds, such as Empoasca fabae 

 (Harris), fig. 35, are among the destructive pests of beans, pota- 

 toes, grapes, apples, and other plants. The cicadas, tree hoppers, 

 spittle bugs, and lanternflies also belong to this order. 



Mallophaga 



Chewing Lice 



Wingless, flattened insects with short anten- 

 nae, short legs, inconspicuous mouthparts, 

 and no tails on the posterior end of body. 



They are found exclusively on the bodies of birds and animals. 



The young have the same general shape and habits as the adults 



and are found with them. Individuals of 



most of the species move about with consid- 

 erable rapidity. Many of them are very 



prettily banded and colored, as is the 



chicken head louse, Lipeurus heterographus 



Nitzsch, fig. 36. Anyone who has worked 



with domestic fowls or animals has seen 



members of this order scurrying along the 



feathers or hair. These insects feed on 



what they can chew 



from the surface of 

 the skin and in some 

 cases are known to 

 injure their hosts. 



Fig. 36. — Mallophaga. 

 Lipeurus heterographus, 

 a chewing louse found 

 on the heads of poultry. 

 Actual length about 0.1 

 inch. 



