456 Journal of Agricultural Research voi. xviu, no. 9 



as the time of emergence draws near. It shows the organs of the adult 

 in rough outline, the wings, however, being represented by very small 

 rudiments. 



PUPARIUM 



This is at first yellow in color, turning to brown, and is usually opaque. 

 It is 2.7 mm. in length by 0.9 mm. in breadth, bearing the minute larval 

 spiracles anteriorly on each side of its tip and the posterior ones behind. 



Fig. 4. — Full-grown larva of Oscinisfrit. X 36. 



Neither of these is functional, since they do not connect with the spiracles 

 of the pupa. (Pi. 57, B.) 



ADULT (ph. 57. a) 



The following description of the adult has been drawn up with the 

 aim of including all common variations. 



MAIvE AND FEMALE 



Length i.i to 2 mm. Head, thorax, and abdomen black. Front in well-matured 

 specimens wider than one eye, usually a little narrower in specimens not completely 

 hardened before killing. Frontal triangle shining black, reaching usually almost to 

 the root of the antennse, but shorter in many specimens, at shortest only a little over 

 half the length of front; the remainder of the front outside the triangle is opaque black. 

 Face black, rather concave, its lower edge sometimes 

 yellowish. Vertex bearing one outwardly directed, minute 

 bristle near the comer of the eye; a minute, convergent 

 pair of ocellars, and behind them a pair of also convergent 

 /T ^ V ones on the occiput ; a row of three or four small hairs 



^^^/"^ along the inner edge of the eye in the opaque part of the 



Fig. s. — Oscinis frit: Mouth front; a pair of hairs at the edge of the mouth also, 

 hooks of full-grown larva. An tenuEe black, third joint rather large, round; the arista 

 More enlarged than in figure 4. ^.jth very minute pubescence, beyond its basal fourth often 

 lighter in color, rarely almost white when viewed against a dark background. Probos- 

 cis and palpi black. Bucca (side of head below eye) usually about one-sixth the height 

 of the eye, but varying from one-fourth to one-tenth or less, the cause of this variation 

 being usually the greater or less drawing up of the under part of the head in drying. 

 Thorax with length, breadth, and height about equal; dorsum subshining to shining, 

 with minute dark hairs usually arranged in rows lengthwise. One pair of minute dorso- 

 central bristles before the scutellum, far apart; one supra-alar, two or three notopleural, 

 one humeral, all small. Scutellum of ordinary form, neither flattened nor elongated. 

 Pleiuse shining black, without bristles. Halteres yellow. 



Abdomen black, subshining, rarely the first segment yellowish; the black color 

 extending underneath to the soft part, which is usually paler. Male genitalia often 

 protrude, showing a pair of distinct claspers curved backward, but these may be 

 retracted and invisible. Abdomen of female pointed, ending in a minute pair of 

 palpus-like organs, at tip of the telescopic, 3-jointed ovipositor when the latter is 

 extended (fig. 6), but ordinarily so retracted as to be barely visible. 



