INSECTS INJURIOUS TO MISCELLANEOUS CROPS 373 



fringe of long hairs. When at rest the wings lie together along 

 the back. 



The thrips belong to a quite distinct order of insects, the 

 Thysanoptera (or Physopoda), species of which are commonly 

 found in the flowers of the rose and clover. The mouth-parts 

 are quite different from those of any other order of insects, being 

 intermediate between those of biting and sucking insects, the 

 mandibles being reduced to bristle-like structures. Their man- 

 ner of feeding does not seem to be clearly understood, though 



FIG. 314. The onion thrips (Thrips tabaci Lind.) very greatly enlarged. 

 (Photo by Quaintance.) 



Professor Quaintance states that the onion thrips frequently 

 rasps off and swallows pieces of leaf tissue. However, they are 

 able to destroy the surface tissue of the leaf so that it wilts, 

 and fields badly affected become blighted and white. . 



This species has quite a list of food-plants, cabbage and cauli- 

 flower often being considerably injured. Among others may be 

 mentioned turnip, kale, sweet clover, squash, cucumber, melon, 

 parsley, tomato, and several common garden flowers and weeds. 



Life History. The eggs are slightly less than .01 of an inch 

 long too small to be visible to the unaided eye elongate, and 

 curved somewhat kidney-shaped. They are laid singly just 

 beneath the surface of the leaf and hatch in about four days. 



