58 U.S. NATIONAL MUSEUM BULLETIN 25 6 



coalesce with the lateral ones. On the apical segment is an irregular 

 brown patch. A long seta arises from all the spots. In younger larvae 

 the spots are larger and often give the appearance of transverse bands. 



The life history may be briefly summarized as follows: Eggs are 

 deposited singly on the tips or sides of the spines or fine spicules. The 

 larvae are solitary in habit and tunnel freely in the segments, often 

 transferring from one joint to another. The rather flimsy cocoons are 

 spun either within the hollowed-out segments, among debris, or just 

 beneath the soil surface. The length of the life cycle is irregular, but 

 both in Argentina and in Australia there are usually two complete 

 generations and a third partial generation annually. The summer 

 generation is comparatively short, the winter generation much longer. 

 The partial generation occurs in the autumn and represents the 

 earlier or more rapidly developing progeny of summer generation 

 moths. 



Like most of the cactus phycitids, the moths do not feed, or at least 

 do not require nourishment. Emergence occurs in the early hours of the 

 evening, and mating occurs the same night. In confinement the moths 

 usually survive for from 3 to 9 days, but a longevity of 1 6 days in Febru- 

 ary (summer) has been recorded, while females have deposited eggs on 

 the twelfth night after emergence. The proportion of female moths 

 averages 47.5 percent; during rearing work over a period of several 

 generations the lowest and highest figures for this sex were 42 and 51 

 percent, respectively. 



The females are more fecund than those of most cactus phycitids 

 studied. The highest number of eggs obtained from one female was 

 376; in this instance the actual record was 751 eggs laid by two females. 

 Another female deposited 342 eggs. On another occasion two females 

 laid a total of 545 eggs during one night. Other high returns are 315 

 eggs per female from 3 females, 293 fiom 73, 265 from 96, and 185 

 from 1,193. 



In breeding work from generation to generation with large numbers 

 of moths, averages of from 150 to 190 eggs per female have been 

 obtained frequently. These figures indicate generally a greater fe- 

 cundity than that of Cactoblastis cactorum, although individuals of the 

 latter insect have deposited as many as 392 eggs. The first eggs are 

 usually laid on the night following emergence, and oviposition may 

 continue throughout the life of the female. A female that lived for 13 

 days deposited eggs on 10 of 11 successive nights, as follows: second 

 night, (24 hours after emergence) 20; then in succession, 207, 30, 24, 

 9, 14, 0, 20, 9, 7, 2: a total of 342 eggs. The greatest number of eggs 

 is nearly always produced on the second and third nights following 



