1921 ENTOMOLOGICAL SOCIETY. 67 



It is very hard to estimate with accuracy the losses involved when a fairly 

 thickly settled district such as the Fraser Valley is subject to the attacks of 

 hordes of blood thirsty mosquitoes, but there are very few industries necessitating 

 outside labour that are not seriously affected. The picking of small fruit is ham- 

 pered, general farm labour is hard to obtain, work in the woods is almost impos- 

 sible and, in 1920, most of the labour camps in the affected district were closed 

 during the worst of the scourge. In places, the construction of roads and high- 

 ways was held up. Cattle became emaciated and the drop in milk production 

 was very marked. During 1920, in the worst affected places, even hens stopped 

 laying eggs as they were unable to rest at night owing to the attacks of mosqui- 

 toes. In spite of screens, mosquito dope, and the general use of smudges, the 

 inhabitants of the affected district suffer terribly from the winged pest that makes 

 life a misery. 



The Lower Fraser Valley has a fairly rich mosquito fauna, twenty specie9 

 coming to hand during the two years, 1919 and 1920. Of these, two only consti- 

 tute the really serious pest as conditions are not suitable for the development of 

 the others in very large numbers. 



Flood Water Mosquitoes. 



Aedes aldrichi Dyar and Knab. This is a very small sage-grey mosquito with 

 a central, divided brown line on the thorax. The abdomen has crisp, white bands, 

 and the legs are dark and unhanded. The species is the dominant one in the 

 Lower Fraser Valley, and breeds mainly in the flood pools in the alder-bottom 

 areas bor-dering the river. The larva, previously unknown, was taken for the 

 first time by the writer this summer. The only other records we have of this 

 insect come from Idaho and Montana. 



Aedes vexans Meigen. A medium-sized, dusty^brown mosquito. The abdom- 

 inal bands are strongly constricted in the centre and the legs have small rings at 

 the base of the tarsal segments. This species is second in importance in the 

 Lower Fraser Valley and although not so abundant as Aedes aldrichi, it sometimes 

 occurs in enormous numbers. 'Open flooded meadows and prairies are the main 

 breeding places, although great numbers also breed in the alder-bottom flood pools. 

 The species is a very comimon one both in Europe and America. 



Aedes cinereus Meigen. A very small species with a rusty brown thorax 

 and unbanded black legs. The abdominal segments are usually unhanded but there 

 is a broad, white stripe along the side of the abdomen. The species is a fairly 

 common one in the Lower Fraser Valley but is comparatively unimportant. The 

 larvse are found in shallow protected surface pools, as well as in flooded alder- 

 bottoms. 



General Breeders. 



Culex tarsalis Coquillett. This fairly large brown mosquito has a very 

 striped appearance. The legs have broad bands at the base and apex of the tarsal 

 segments and the proboscis has a broad crisp stripe, the abdomen is fairly broadly 

 banded. The thorax is dark chestnut brown and is ornamented with fairly dis- 

 tinct markings. The tip of the wing has an indistinct patch of yellow scales 

 Although generally distributed throughout the valley, this species is not a very 

 abundant one. It is a vicious and persistent biter, and enters houses. The larvse 

 are found in a great variety of habitats, roadside ditches and open flooded meadows 

 bein£ the chief among them. 



