ORDER DIPTERA 



235 



adjacent to one another, the mines soon coalesce, and miners 

 with such habits have, in the broad sense, been termed 

 gregarious. All true linear miners are solitary. The blotch 

 miners have both solitary and gregarious habits. 



Fig. 71. Types of Dipterous mines. 1, Phytom. obscurella nigritella, 

 $, Agrom. curvipalpis; 3, Phytom. albiceps; J^,\Agrom. pusilla; 5. Agrom. 

 coronata; 6, Agrom. borealis; 7, Scaptomyza adusta; 8, Agrom. ulmi. 



The Anthomyiidae make large, blister-like mines, which 

 frequently cover the entire leaf but seldom cause it to wilt, 

 ^lien the leaves are young and the plant is growing rapidly, 

 the injury is entirely overcome. The Trypetidae, on the 



