PSYCH K. 



NOTES ON HYBRIDS OF SAMIA CYNTHIA 



PROMETHEA. 



AND ATI'ACUS 



CAROLINE GRAY SOULE, BROOKI.INE, MASS. 



Having been told that it was difficult, 

 if not impossible, to obtain fertile eggs 

 from cross-mating these species I care- 

 fully watched the normal mating of 

 both species for suggestions which 

 should help in obtaining hybrids. 



I found that the males were so 

 excited by the odor of the females that 

 they would fasten their claspers on any 

 part of a female's body or even on each 

 other. Therefore I put female cvii/Znasm 

 a cage toward which the wind blew from 

 a cage containing a female promethea, 

 and introduced \\\\\t. promi-theas. After 

 a few minutes of the wild flight and quiv- 

 ering of the wings characteristic of the 

 mating oi promtthca the males mated 

 the lynthia females as readily as if they 

 had been of their own species. 



The same experiment was tried with 

 cyiilhia males and proiiwthea females 

 and with equal success so far as mating 

 went. 



Of the eggs I sent away more than 

 three fourths and of these I know the 

 results of those sent Miss Eliot only. 



Only two of m)- eggs laid by cyiithia 

 females hatched, and the larvae were 



normal cynthia larvae except that in the 

 last stage they were greener. 



Of the eggs laid h\ p?-omcthca feinales 

 all mine and Miss Eliot's hatched and 

 gave great variety, though we divided 

 them into " the promcthca form" and 

 "the cynthia form," for convenience in 

 referring to them. 



There were more of the ^^ piomcthca 

 form" and these were normal promethea 

 larvae except that in the last stage some 

 had very noticeable blue patches around 

 the black dots of the lateral and stigma- 

 tal rows. Rearing them side by side with 

 a brood of normal, pure proinctheas I- 

 could see no other difference. 



The " cynthia form" larvae were like 

 the promcthcas in the first two stages, 

 but after the second moult they could 

 be separated from those, though they 

 varied among themselves. 



Their heads were yellow barred with 

 black. Some bodies were yellow with 

 transverse black lines, black tubercles 

 on the first two and anal segments, and 

 yellow tubercles elsewhere. The legs 

 were black, the props yellow. 



Others had two yellow tubercles, 



