BIOLOGICAL STUDIES ON THREE APHIDID^. 



163 



one egg to that of another, Usuall}', however, the interval was one of 

 several days, temperature being the controlling factor. My aphides 

 always laid eggs until the temperature got down to 42° F, In a num- 

 ber of cases, upon the death of an oviparous female the body was 

 examined, and with only one or possibly two exceptions, eggs were 

 found therein. These facts show that there is no definite nmnber of 

 eggs for a sexual female to lay, but that eggs continue to be laid as 

 long as she lives, provided the temperature is not too low. Some indi- 

 viduals of this sexual generation lived until January 17, 1907, though 

 most of them died in November and December, 1906. During most of 

 the month of December the temperature was down to the freezing 

 point, and consequently the females were in a dormant state; as the 

 food plants were dead they certainly obtained no food during this 

 time. The length of life was found to vary up to 83 days, the aver- 

 age, however, in 17 cases, being 57.4 days. The number of molts is 4, 

 the same in this generation as in the viviparous. Table XIV shows 

 the periods betw^een molts in the 7 cases of which record was made. 



Table XIV. — Periods of molts of Siplia flara, oviparous grnrratioii, 1906. 



DESCRIPTIONS. 



Siplia (Cliaitophonis) flara Forbes. 



This aphis does not belong to the genus ChaitopJwrus, which has 

 6 antennal segments (or 7, counting the filament), and should doubt- 

 less be placed in the genus Siplia of Passerini, which is described as 

 having 5 antennal segments, or G with the filament, the third segment 

 and filament longest ; the cornicles tuberculiform. 



. VIVIPAROUS GENERATION. 



Before first molt and less than £4 hours old. — Citron-j^ellow 

 throughout. Legs and antennse somewhat transparent and of a 

 lighter tint than the body color. Antenna apparently only 4-seg- 

 mented. One sensorium is present at the extremity of the third 

 segment. Eyes brownish red. Numerous tuberculate spines on the 



