42 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 39 



A great many of the serious insect pests, including kinds that 

 attack field crops, stored products, and household goods, are 

 beetles. Beetles of one group that have the front of the head pro- 

 duced into a snoutlike structure, as Curculio caryae (Horn), 

 fig. 41, are called weevils or snout beetles. This group has mag- 

 gotlike larvae and contains many of our worst pests, such as the 

 plum curculio, cotton boll weevil, alfalfa weevil, and clover weevil. 

 Bizarre and striking forms occur in many beetle groups, notably 

 among the scarab and long-horn beetles. The largest in Illinois 

 is the rhinoceros beetle, Dynastes tityus (Linnaeus) ; the male, 

 shown on the cover, has long projections on both head and 

 thorax; the larva lives in rotten wood. 



Tree-boring beetle larvae are destructive to many orchard, orna- 

 mental, and native trees. These include chiefly the round-headed 

 borers, adults of which are long-horn beetles ; flat-headed borers, 

 adults of which are usually flat and metallic; and engraver or 

 shot-hole types, adults of which are small and bullet shaped, and 

 are called bark beetles. 



A few families of beetles have both the adults and larvae fitted 

 for aquatic life. Well known among these are the shining whirli- 

 gig beetles. 



Neuroptera Insects with two pairs of wings, both about 



Lacewings the same size and shape and intricately net- 



and Their ted with veins. Antennae long and slender, 



Allies mouthparts fitted for chewing, posterior 



end of the body without tails. The green 



lacewings of the genus Chrysopa, fig. 42, are our commonest 



members of this order. The young of this order are entirely 



Fig. 42. — Neuroptera. Chrysopa nigricornis, a green lacewing. When 

 handled, members of this genus give out a very penetrating and disagreeable 

 odor. Actual length 0.6 inch. 



