AUG 2 }m 



m THE AFFINITY OF OUR WILD A^D 

 DOMESTIC SILKWORMS. 



By C. SASAKI. 



Professor of Entomology, Agricultural College, Imp. Univ., Tokyo. 



With PL 111. 



The wild silkworms, which are vulgarly called Kawako, Kuwaoko, or N<>vaok <_<, 

 are widely distributed in almost all parts of our empire, where mulberry trees are 

 planted. They are more or less found on the trees every year, but they do no 

 greater harm than the other lepidopterous larva 1 that are found feeding on the 

 same trees. 



The eggs of the wild silkworms hatch out usually in the latter part of April, 

 nearly at the same period with our domestic form (Bombyx mori, L.). From the 

 end of June to July, they, becoming mature, spin a light yellowish cocoon 

 within a folded leaf. The winged insects may appear at the end of two or 

 three weeks after the formation of the cocoon, ami lay eggs on branches or twigä 

 of mulberry trees. The eggs hatch out in from two to three weeks after they are 

 laid ; but the hatching is sometimes much delayed. Thus the growth of the larva' 

 becomes very irregular, as we meet with various stages of their growth within the 

 same period, and consequently the winged insects begin to appear in September, 

 and continue to do so till November. The eggs deposited by these on the stems or 

 branches of mulberry trees, pass the winter and hatch out in the following 

 spring. 



It seems however that the moth breed generally twice in a year, or even 

 more frequently in a more favorable condition. 



On the wild silkworms, Mr. H. Pryer wrote some accounts in his catalogue 

 of the lepidoptera of Japan, in which he says: "Bt.vibtjx sp. Yokohama; a 

 wild form of the cultivated silkworm. The larva anil imago are considerably 

 darker ; it spins a much lighter cocoon than the domesticateli insects ; feeds on 

 the mulberry. " This is all that he wrote on the wild silkworm, and he did not in- 



