CACTUS-FEEDING INSECTS AND MITES 127 



at the base of the plants; hibernation is not complete, since the insects 

 will become active and feed to some extent on warm sunny days. It is 

 possible, however, that at higher elevations and in colder latitudes of 

 die United States C. vittiger hibernates completely for 2 or 3 months. 



The overwintering adults oviposit in spring from March to May in 

 Texas and Mexico and from April to June in the more temperate 

 regions. In the Brownsville district of Texas C. tabulata adults may 

 deposit eggs in February if the weather becomes warmer; in Mexico 

 eggs are frequently laid during February. The first generation reaches 

 maturity in May to July, and oviposition extends from July to No- 

 vember. The second generation larvae develop to adults at any time 

 between August and November, while a small proportion, representing 

 the tail-end of the generation, may spend the earlier months of winter 

 as large nymphs. The adults of the second generation do not oviposit 

 until spring. 



The adults are capable of sustained longevity. The following records 

 of adult life were made under cage conditions in Australia: 



C. tabulata. Adults of the first summer generation lived for a 

 maximum period of 350 and 424 days in the case of a male and a female, 

 respectively. The female laid eggs during January to April and again 

 during August to December; the interval between the first and last 

 batch of eggs was 390 days. A female of the second summer generatio n 

 lived for 330 days and deposited eggs over a period of 170 days from 

 August to January. 



C. canvona. A female of the first summer generation survived for 

 343 days, depositing eggs during January to March and again in 

 October and November, a period of 10 months between the first and 

 last eggs. 



C. vittiger. A female of the second summer generation survived for 

 542 days ovipositing freely in October and November and laying a few 

 eggs in February and March. 



Parasites. — The tachinid Trichopoda pennipes has been reared in Texas 

 from C. tabulata, C. canyona, and C. vittiger, and in Florida from C. vittiger. 

 This insect attacks many Heteroptera, and although a common enemy 

 of Chelinidea, appears to exercise little control. 



An egg-parasite Hadronotus sp., has been reared from eggs of C. 

 tabulata and G. vittiger at Uvalde, Texas, and from eggs of C. tabulata 

 at San Luis Potosi, Mexico. One parasite issues from each egg. The life 

 cycle was completed in 20 to 26 days at Uvalde in September and 

 October. In September 1930, 80 percent of the Chelinidea eggs collected 

 at Uvalde were attacked by this insect. 



