ORDER THYSANOPTERA 



91 



thri]is. It occurs on quite a large variety of plants. It is 

 similar to Thrips iritici in size, but different in some micro- 

 scopic details. It is injurious to onions. Massachusetts, 

 Iowa, Colorado, Rhode Island, and Ohio have all reported 



Fig. 51. — The pear thrips {Euthrips pi/ri): adult. Much enlarged. 

 (After Moulton, Bur. Ent., U. S. Dept. Ag.) 



extreme injury from this species. The degree of injury is 

 determined in large part by temperature, moisture, etc. 

 It occurs on many plants besides onions. In dry seasons 

 it becomes very injurious to the onions. The leaves wilt 

 and show whitening, and the injury is easily recognized. 



