OF WASHINGTON. 35 



At first sight, Mr. Coquillett, to whom I took the specimens, 

 determined them as belonging to Agromyza simplex Loew, the 

 " asparagus root-miner," a species of no inconsiderable eco- 

 nomic importance ; but upon a more careful examination dif- 

 ferences were noted by which a separate species may be dis- 

 tinguished from the adults alone. Mr. Coquillett is now in- 

 clined to think that this may be the species originally described 

 as simplex, and that the asparagus miner should perhaps be 

 described as new. Either will fit Loew's description, however, 

 almost equally well ; and, unless it is absolutely necessary, it 

 does not seem desirable to change the name of an insect which 

 has become so well known to economic workers. Moreover, 

 simplex is described from the " Middle States ; " the asparagus 

 miner is common from New England to the District of Colum- 

 bia, and is therefore much more likely to be the subject of that 

 description than is the " linden gall-maker," which at present 

 is known from a single locality, and that in Missouri. 



There follows a description of the adult of the insect under 

 discussion, the gall of which will be readily recognized by ref- 

 erence to figure I. 



Agromyza tiliae, n. sp. 



Color, including head and antennae, shining black. Mesonotum and 

 scutellum a little shiny; abdomen triangular, very shiny. Ocellar tri- 

 angle with the sides forming the apex somewhat concave and longer 

 than the third side, shiny. Wings hyaline, veins black; penultimate 

 section of the fourth vein usually somewhat shorter ' than the posterior 

 cross-vein which is about one-half the length of the last section of the 

 fifth vein. Length 2 to 2.5 mm. 



Described from lo specimens bred from galls collected by 

 Mrs. T. F. Hickey in Jennings, Mo. 



Type. — No. 10928, U. S. National Museum. 



The adults may be distinguished from those of simplex by 

 the size and shape of the ocellar triangle, and by the arrange- 

 ment of the frontal bristles. These differences are plainly 

 shown in figure i at <? and /. It will be seen that the ocellar 

 triangle is much larger in tilicc, and that the sides forming 

 the apex are somewhat concave rather than convex. The 

 frontal bristles in simplex are almost equidistant, v/hile in 

 tilice the four lower ones arie nearer together, and the fifth 

 separated from the fourth by a distance almost twice as great 

 as that between any two of the others. 



* This character is variable. In one of the cotype specimens the pen- 

 ultimate section is only about one-half the length of the cross-vein, 

 while in two other specimens they are approximately equal. 



