INSECUTOR INSCITI^ MENSTRUUS 117 



whenever wet, whether of the same season's deposition or of 

 the previous season's. This is the case with curriei, nigroma^ 

 culis, and trivittatus , the three other species inhabiting the 

 irrigation pools with vexans. 



Aedes trivittatus Coquillett. 



Found only at Laurel and probably confined to the eastern 

 half of Montana. The adults frequent the river bottom by 

 preference, though they must at least make excursions into 

 the prairie, as larvae occurred in temporary irrigation pools a 

 mile and a half from the river. The species is rare and can- 

 not be considered as especially troublesome. 



The egg is thickly fusiform, pointed at the ends, a little 

 flattened on one side, rather large, shining black, laid singly. 



Eggs deposited July 25, 1917, were submerged a few days 

 later and larvse immediately hatched, but leaving many un- 

 hatched eggs in the water. The habit is the same as in curriei, 

 that part of the eggs hatch whenever submerged and that the 

 cold of overwintering is not a necessary prerequisite to 

 hatching. 



Aedes cinereus Meigen. (fiucus Osten Sacken). 



This species is confined to the river bottoms and vicinity in 

 the arid country. The little mosquito is a bad biter in the 

 timber and low willows. Males were seen swarming after 

 sunset at Laurel in the river bottom between arched willows 

 about seven feet from the ground. Also males were netted 

 in willows at Lake Cushman, Washington. In the latter case 

 the swarming could not be witnessed, but was undoubtedly 

 taking place. No specimens were seen on the prairie, nor were 

 larvae bred from temporary irrigation pools in the open. At 

 Missoula an artificial pool under willows was inhabited by the 

 larvae. In New Hampshire I bred the species from roadside 

 pools following rain, together with vexans and canadensis. 

 These three species will, therefore, breed in accidental pools 

 all summer, but only vexans takes advantage of irrigation 

 pools in the open, the other two species being confined to 

 forested country. 



