Oct. io, 1913 
Serpentine Leaf-Miner 
67 
Throughout the entire West the mines were found in limited numbers 
wherever alfalfa is grown. 
From the occurrence of the larvae and pupae in such widely scattered 
points we are led to believe that the insect has long been established 
throughout the alfalfa-growing sections of the West. 
While this leaf-miner does not constitute a widespread menace to the 
alfalfa crop, it works considerable damage in New Mexico, Arizona, and 
southern California, because leaves mined by the larvae are unfit for 
fodder; besides, the changed color of the hay reduces its market value, 
especially if grown mixed with timothy. 
DESCRIPTION OF THE LEAF-MINER, AGROMYZA PUSILLA. 
THE ADULT (FIG. i) 
In view of the great number of synonyms and the impossibility of 
giving descriptions of all of these in this article, Mr. Malloch has drawn 
up the following description, based on a large number of specimens 
in the collections of the Bureau of Entomology and the United States 
National Museum, the better to facilitate the recognition of the insect as 
it occurs in America. 
Male and Female. —Black, shining, marked in most variable degree with yellow. 
Frons, except ocellar region and sometimes a narrow side stripe posteriorly, yellow; 
remainder of head parts, except behind vertex, yellow. Mesonotum with a more or 
less broad yellow margin which never extends distinctly around the anterior or the 
posterior margin; four pairs of dorsocentral bristles present, as well as numerous short 
hairs on disk; humeri with a black spot. Pleurae sometimes yellow, with a brownish 
spot above and shortly behind the coxae, another large one covering the space between 
the fore and mid coxae, and another one between the mid and hind coxae; at other 
times almost entirely black, with the sutures and upper margin yellow\ Scutellum 
entirely yellow, or yellow with black basal side spots, which in some cases extend 
almost around the entire margin and on to the disk. Postnotum black. Abdomen 
yellowish, with dark brownish bases to segments; or black, with pale apices to seg¬ 
ments; or entirely shining black, with the apical segments whitish or yellowish at 
apex. Legs varying from almost entirely yellow, with only the tarsi brownish, to 
almost entirely black, with knee joints yellow; the femora generally less intensely 
black than other parts of legs. Mid tibiae without distinct posterior bristles. Wings 
clear; second division of costa about two and one-half times as long as first section, 
third and fourth veins divergent at extremities; outer cross vein as long as or slightly 
shorter than the section of fourth anterior to it; basal two sections of fourth subequal 
or the second slightly the shorter; last section of fifth vein about three times as long 
as preceding section. Hal teres yellow. 
Length, 1 to 1.75 mm. 
This is a most variable species in color and is very widely distributed. 
THE EGG (FIG. 4) 
The eggs are pale, white, oval, about 0.25 mm. long, and can be frequently seen 
through the epidermis from above. Figure 4, b, shows the egg partly dissected out 
of one of these pits. 
