Table L- 



BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 



—Reproduction and development of the rose aphis, Maerosiphum rosae, in 

 southern California, 1909-10 — Continued. 



Date of birth of female unknown; 



gave birth to first young Jan. 3, 



1910: Number of 



young. 



Jan. 3 2 



4 2 



6 9 



3 - P) 



Total 13 



Average per day 3 



Winged female, red form; gave birth 

 to first young Mar. 3, 1910: 



Mar. 3 5 



4 5 



5 9 



6 5 



Winged female, red form; gave birth 

 to first young Mar. 3, 1910 — Con- 

 tinued. Number of 



young. 



7 5 



8 3 



9 P) 



Total 32 



Average per day 5 J 



Mar. 7. 



8. 



9. 



10. 



5 



5 

 7 

 P) 



Total 17 



Average per day 5| 



Two females were observed that produced 30 and 40 young, respec- 

 tively, after which, they died under normal conditions. They pro- 

 duced young on an average of 2 and 2\ per day for 15 and 20 days, 

 respectively, during the month of December. Other females observed 

 during the same period, but lost possibly before reproduction was 

 completed, gave birth to from 15 to 45 young at an average of 2>\ per 

 day. Two females observed in the month of March, however, pro- 

 duced young at the rate of 5-| and 5§ a day, showing quite plainly 

 how the reproduction was accelerated during the prevalence of 

 warmer temperatures. Two females in October reproduced young 

 at the rate of 5-| a day for 6 days, or until lost. 



From these observations it may be said that this insect is able to 

 reproduce for at least 20 days during the winter in southern California 

 and to give birth to as many as 45 young, while in the warmer seasons 

 the number of young is probably greater and the period of reproduc- 

 tion is considerably shorter. The reproduction experiments were too 

 few in number to justify making any statements more generalized 

 than these. 



LIFE HISTORY AND REPRODUCTION IN THE GREENHOUSE. 



During the fall of 1912 the rose aphis was under the direct observa- 

 tion of the writer in the insectary greenhouse at Washington, D. C, 

 and the life cycle was observed for a few individuals. 



A wingless female born October 10 matured and gave birth to young 

 on October 19, or in 9 days. During the next 7 days she gave birth 

 to 45 young, or an average of 6y per day. 



1 Aphis lost. 



