418 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



induced to bite. All deposited single batches of eggs and then died 

 despite the utmost care without ovipositing a second time in contrast to 

 the midseason fem.ales which frequently deposit two and sometimes three 

 batches of eggs in captivity under similar circumstances. The study of 

 the collection chart of both males and females shows the emergence of 

 the first generation of the year reaching its peak during the first of June 

 and is followed by a rapid decrease in num^bers that would have been re- 

 placed by a m.ore sustained curv^e had there been m.ore than one series of 

 deposited eggs. It is interesting to note the three peaks that denote 

 the em.ergence of first brood males in April, Ma}- and early June and 

 hazard at their connection with the three peaks of over^vintering females 

 that were abroad in February and March (the emergence from, hiber- 

 nation being unusually gradual during the year in question.) 



The individuals of this first generation which began to em.erge from pu- 

 pation in May and June are relatively few in number. This may be due 

 to the sm.all num,ber of eggs deposited by the ovenvintering fem.ales as 

 advanced above, or it m,ay be due to the hazards of life at this time of 

 year. The average low temperature prolongs the larval life of this 

 generation to approximately two m.onths during which tim.e they are 

 constantly exposed to their predaceous and parasitic enem.ies and to the 

 danger of being washed out by high water, a factor which disposes of 

 m.any m.osquito larv^ae breeding along the edges of stream.s fed by melt- 

 ing mountain snows. 



Fertilization of the fem.ales takes place immediatelv upon emergence. 

 The males em.erge first and m,ay be seen hovering over or near the breed- 

 ing places in small swarms awaiting the appearance of the females. The 

 universal fertility of captured wild specimens points to a very perfect 

 biological arrangement enabling an infallible fertilization of the female 

 and strengthens Knab's conclusion based on his observation of anopheline 

 mating that the female seeks out a male from, the hovering swarm. 



The egg deposition of this first generation begins within a few days of 

 its emergence. The average number of eggs deposited in a single laying 

 by A. occidentalis is according to Herms and Freeborn, approximately 

 200 eggs, a m.uch greater number t.han had previously been supposed. 

 The number of layings can not be estim-ated with our present technique. 

 The two biological factors that have hindered us in this work are (1) in- 

 ability to produce copulation with bred specimens in captivity which 

 forced the use of wild material regarding whose previous egg deposition 

 we had no check and (2) inability to keep laying females alive in captivity 

 until their ovaries no longer showed the reappearance of a new batch 

 of eggs following the deposition of the second and on one occasion a third 

 laying. Ever\' attempt was made to reproduce natural conditions in 



