59 



It may be pointed out, that the 0. excrucians-kwYx, in contrast to those of 

 0. communis, almost always lie on the bottom, often on the dorsal side, or very 

 often are found hanging down from water plants; they rarely come to the surface, 

 brushing the bottom and the plants free from detritus. - The life history of the 

 species is the same as for the other mosquito larva' in drying ponds. They are hatch- 

 ed immediately after the melting period, probably a little later than 0. communis, 

 they left the pond on 15/v; a few days afterwards the ponds were quite dry and 

 did not get water before the spring. The mosquito have only one generation. In one 

 of the ponds which got water in December, a few larva; developed but did not 

 hibernate, dying out under the ice. The number of larva 1 in the ponds hitherto ex- 

 plored is always slight; I have never found them in huge swarms; also as imagines 

 the mosquitoes are rare; I have only found them in the vicinity of the ponds 

 where they were hatched; they bite vigorously, sitting deep down in the grass, and 

 Hying out when this is moved. A few have been observed in the latter part of August. 



Geographical distribution: It has hitherto only been found in North- 

 eastern North America (H. D. K. 1917 p. 691). 



7. O. lutescens (F.). 



O. fletcheri (Couuillet). 



Tab. VI. 



Description. Female: Proboscis moderate, vestiture of brown-black scales. 

 Palpi stout, rather long, more than one-fourth as long as the proboscis; vestiture 

 of black scales with a few pale ones. Antenna? with tori subspherical, with a cup- 

 shaped apical excavation, ocher yellow, on the inner side black and with small, 

 flat, broad whitish scales. Occiput rather broad, clothed very broadly with dense, 

 narrow curved brassy scales on the vertex, a large patch of golden brown ones on 

 each side close to the eyes; bristles bordering the eyes pale brown. 



Prothoracic lobes elliptical, well separated, brownish, clothed with narrow, gol- 

 den scales below, golden-brown ones above and pale bristles. Mesonotum black, a 

 broad median stripe of narrow curved golden-brown scales, a detached stripe of 

 similar scales on each side on posterior half; sides of disk and ante-sculellar space 

 clothed with pale brassy scales. Scutellum trilobate, each lobe with a large group 

 of whitish bristles. Pleura? gray, the coxa? pale brown. 



Abdomen subcylindrical, flattened, the posterior segments tapered; dorsal vesti- 

 ture nearly wholly of dull ochraceous white scales intermixed with a few black 

 ones, these latter predominating along lateral margins, forming an ill-defined stripe 

 becoming obsolete towards the tip; no traces of bands along the borders of the 

 segments, venter similarly coloured, the black scales forming an ill-defined median 

 longitudinal stripe. Cerci black. 



Wings rather broad, hyaline yellow irridiscent; petiole of second marginal 

 nearly half as long as its cell, that of second posterior cell about as long as its 

 cell; basal cross-vein nearly its own length distant from anterior cross-vein, out- 

 s'- 



