66 DIPTERA OF NORTH AMERICA. 



wings and the tip of the borer being black. In darker individuals, 

 the following markings appear successively: 1. A black double 

 spot in the middle of the anterior border of the thorax ; 2. A 

 black spot on each side of the scutellum ; 3. A broad black stripe 

 on each side of the metanotum ; 4. The black posterior portion of 

 the lateral stripes ; 5. The black anterior portion of the lateral 

 stripes ; 6. The double stripe in the middle of the thorax, abruptly 

 ending in its centre. The head is rather bright yellow ; front very 

 prominent, face much receding ; opening of the mouth not widen- 

 ed ; palpi and proboscis short, yellow, the bristle with a very short 

 pubescence. Frontal bristles black, the superior ones considerably 

 stout, two of them on each side in the male assume the shape of 

 straight spines, a little incrassatecl at their tips ; in smaller males, 

 however, these spines are not seldom only little stouter than in the 

 females, and of the ordinary form. The lateral border of the thorax 

 and the superior border of the pleura? may have a pale yellow 

 color in life ; in dry specimens they are very whitish. From the 

 pale yellow scutellum a broad pale yellow stripe extends to about 

 the middle of the thorax. Hairs and bristles of the thorax black. 

 Scutellum with four black bristles. Abdomen proportionately 

 very narrow, with rather long black hairs. Borer about half as 

 long as the abdomen, with the tip only blackened. Legs yellow, 

 anterior femora with black bristles on the under side. Wings 

 narrow and very long, more elongated and pointed in the males 

 than in the females, but not always in the same degree ; the brown- 

 ish-yellow stripes and bands leave the following clear spots : 1. A 

 space near the costal border between the transverse humeral vein 

 and the tip of the auxiliary vein, and having usually a brownish 

 spot in its middle ; 2. An oval space immediately below the 

 stigma between the third and fourth longitudinal veins ; 3. A tri- 

 angular space immediately beyond the tip of the first longitudinal 

 vein, and reaching from the costal border as far as the third longi- 

 tudinal vein ; 4. An arcuated band running obliquely from the 

 costal border between the two transverse veins as far as the fifth 

 longitudinal vein ; 5. A triangular space on the posterior border 

 filling up the second posterior cell, with the exception of an edge 

 along the veins ; 6. An arcuate oblique seraifascia beginning on 

 the posterior border before the tip of the fourth longitudinal vein, 

 and running as far as the third longitudinal vein ; t. The alary 

 appendage, the posterior angle of the wing, and a large space 



