144 U.S. NATIONAL MUSEUM BULLETIN 25 6 



egg to the egg-producing female may occupy 180 days, while in some 

 cases the summer life cycle is probably as short as 30 days. 



The male crawler moves about freely, and inserts and withdraws 

 the proboscis frequently; the feeding position may be changed several 

 times within 24 hours. Finally it crawls onto a female culture or colony 

 of cultures and spins an oval white silky cocoon, in which the last larval 

 and pupal stages are completed. The male life cycle has been deter- 

 mined at 45 to 59 days in October-November in Australia, including 

 15 to 19 days in the cocoon; in January a cocoon stage of 12 days has 

 been recorded. The perfect male insect is an active fly, with two delicate 

 white wings, and with two lengthy white anal filaments; the imperfect 

 mouth parts are incapable of absorbing nourishment. 



Oviposition by one female may extend over a considerable period. 

 Records of the egg-production period from individual females during 

 summer varied between 35 and 52 days in one experiment with D. 

 opuntiae; in another, three/), opuntiae females each oviposited for 19 days 

 and three D. conjusus females for 19 to 23 days. The greatest number of 

 eggs obtained from a female D. opuntiae was 420; ten individuals yielded 

 an average of 350 eggs. The highest production from a D. conjusus 

 female was 361 eggs; three individuals laid an average of 329 eggs. 

 When egg laying is completed the empty body shrivels, and the female 

 dies. 



Parthenogenesis is a usual procedure. Crawlers from fertilized and 

 virgin females appear identical. Two fertilized females produced 720 

 crawlers, of which 123 were males; two virgin females produced 660 

 crawlers, of which 1 38 were males. 



GENERATIONS 



Our experience with the various cochineals in North and South 

 America and in Australia has indicated that there are either four or 

 five generations annually. In warmer climates a fifth generation is more 

 or less frequent; where winters are more severe, four generations tend 

 to occur. However, the generations are not regular, even in the same 

 locality. The females continue to reproduce for from 3 to 6 weeks, and 

 even longer in the cooler months. Temperature variations and other 

 climatic changes influence reproduction, and the succulence of the 

 food supply affects the rate of development. 



The life cycle in the summer months occupies from 4 to 10 weeks, 

 the average period being 6 to 8 weeks. There are usually three gener- 

 ations during the 6 summer months (October through March in South 

 America and Australia, April through September in North America). 

 During the winter, both in North and South America, the life cycle 



