86 



ENTOMOLOGICAL NEWS 



[xxxii, '21 



TABLE II. 



Larval and pupal instars of twenty-one individuals, 1918, 

 Sacramento, Calif. 



I 'revious to the final ecdysis the larva casts three skins ; 

 the average length in days for the four larval instars was 

 found to he respectively 4.6, 3.7, 4, 7.1 (8 individuals), but 

 the average for the last instar included 2.1 days from the 

 time the larva tailed (attached itself for pupation) until the 

 molt to the pupa actually took place. 



The increase in the duration of the larval and pupal stages 

 synchronized in general with the gradual lowering of tempera- 

 ture. Thus in October the larval stage was over twice as long 

 and the pupil stage four times as long as the corresponding 

 stages in July. 



The cycle from egg deposition to adult emergence is passed 

 in July in about 20 days, towards the end of September in 

 about 33 days, a month later in about 50 days. Allowing an 

 additional ten days to cover the period from emergence of the 

 beetle to oviposition, it is found that the life cycle in mid- 

 summer is passed in a month. It appears doubtful if there 

 are ever more than five generations in a year. All the experi- 

 mental larvae recorded above were supplied only with rose 



