4 MOSQUITOES 



as thoug-h they were hibernating-. In such dry spells 

 the males generally die and the gravid females live over. 

 This is also the case in winter hibernation in the north ; 

 females are, as a rule, impregnated when hibernation time 

 comes, and they live until the ice melts and the weather 

 becomes of the proper temperature for the laying of eggs. 

 As shown by recent observations by Mr. J. Turner Brake- 

 ley and Dr. John B. Smith, larvae, on the approach of 

 wdnter, may be frozen up in the ice and when thawed out 

 resume their growth, so that many undoubtedly hibernate 

 in this way. 



Parthenogenesis Among Mosquitoes. 



We have just stated that the males impregnate the 

 females and then die during- the early winter or during 

 the early part of the dry spell in tropical countries, but 

 there is evidence that parthenogenesis, or virgin birth, 

 sometimes occurs with mosquitoes, as it does with so 

 many of the lower forms of life. 



Professor V. L. Kellogg, of Stanford University, reared 

 in a covered jar, from the pupa a female mosquito Avhich 

 almost immediately laid eggs. There was no other mos- 

 quito in the jar and certainly no mating. From these 

 eggs there hatched larvae, which grew very slowly and 

 nearly reached full growth before they died. None of 

 them succeeded in reaching the pupa stage. It is possi- 

 ble that they died on account of their abnormal birth, but 

 there is also the possibility that they died from lack of 

 proper food, and that under other conditions adults 



