October, '21] severin: beet leaf hopper 435 



the cultivated area correspond to the same months in which the second 

 to the fifth generations were reared from the pale sreen leafhoppers as 

 follows: June- July; July -August; September-October and October- 

 November. 



The minim,um. preoviposition period of the first brood adults required 

 three days during July at a mean temperature of 80.3°F. The pre- 

 oviposition period of the dark oven^'intering females varied from 3-4^ 

 months, hence no eggs were deposited during the autimm. The follow- 

 ing* percentages of dark females collected during the winter on the Coast 

 Range had fully developed eggs in the ovaries: December 4%; January 

 52-64% and February- 86-99%. 



The longevity of 60 m.ales and 40 females of the spring brood collected 

 on April 28, 1919 on the plains near the foothills of the Coast Range was 

 determ,ined in a cage out-of-doors and varied as follows: males, three 

 m.onths ; fem.ales, four m.onths. The longest adult life of four generations 

 which were bred varied as follows : 



The longevity of the dark overwintering adults can be determined 

 approxim.ately under natural conditions. Dark specim.ens first make 

 their appearance in August in the cultivated area and are abundant 

 from. Septem.ber to Novem.ber. The first m.arked reduction in the 

 number of dark males occurred during December in both the cultivated 

 area and on the plains and foothills and from. Februarys to March, m.ales 

 are very rarely taken. The length of adult life of the dark males 

 is about four m.onths. The first m.arked reduction in the num.ber of 

 dark fem.ales occurs during March and April. In all probability, the 

 last dark fem.ales are at the end of their natural life by the tim.e that the 

 pasture vegetation becom,es dry. It is doubtful whether any dark 

 fem.ales which flew to the plains and foothills during the autum.n, return 

 to the cultivated area during the spring. The longevity of the dark 

 overwintering fem.ales is about seven or eight m.onths under natural 

 conditions. It is evident that the longest adult life in cages, of four 

 broods which were bred, is greatly prolonged and does not occur under 

 natural conditions. 



Light colored adults rarely winter over, fom.e specim.ens collected 

 on the plains and foothills from. October to January had m.ature eggs in 

 the ovaries, while others like the dark fem.ales, winter over without depos- 

 iting eggs during the autumn. 



