HOW TO KNOW THE IMMATURE INSECTS 



There are about 52,000 species when counting the Homoptera and 

 Hemiptera together. Practically all the members of Homoptera are 

 phytophagous and mostly injurious to agriculture. Except for the ci- 

 cadas, the Homoptera are mostly small insects. The aphids or plant 

 lice, the scale-insects, the spittle bugs or froghoppers, the treehoppers, 

 the leaf hoppers, the whiteflies, the jumping plant lice and the plant- 

 hoppers are all destructive insects. 



17a. Never any trace of wings 

 or wing pads; compound 

 eyes never present; worm- 

 like; a feeding and active 

 stage. Fig. 71.. .LARVAE. .18 



The members of this active feed- 

 ing stage of the insects developing 

 by complete metamorphosis vary 

 widely in structure, size, habits, 

 color, etc. They are usually heavy 

 feeders and often represent the 

 most destructive stage of the spe- 

 cies. They may be short or long 

 lived which has much to do with 

 the length of the Ufe cycle. 



Fig. 71. a, Hydropsyche sp.; 

 curcuho, Conotrachelus n e 

 (Herbst.); c, Pterostichus sp., 

 ra vinulo L. 



b, Plum 



n u p h a r 



d, Ceru- 



17b. Legs and wing 

 pads encased in 

 a n extra mem- 

 brane, not used 

 for locomotion, 

 usually incapable 

 of being moved; 

 compound eyes 

 visible imless ad- 

 ults are eyeless; 

 a nonfeeding and 

 resting stage. 

 Fig. 72. PUPAE. 45 



Fig. 72. a, Puparium of frit fly, Oscineila frit (L.); 

 b. Pupa of Hesperophyiox sp.; c. Pupa of Leptino- 

 torsa decimlineato (Say); d. Pupa of Vespo mocuto- 

 to Kirby; e. Pupa of Corydoius cornutus (L.). 



40 



