BOMBYCID^. 295 



getting an entire brood of dark worms, which he regarded as 

 a sign of increased health and strength in the larvae, thus 

 proving that the dark worms were of the original race, which 

 also agrees with the colors of the numerous species of the genus 

 of which he has, with others, made known nearly twenty. The 

 author also considers the white cocoons as a strong sign of de- 

 generacy, arguing that the good quality of the silk produced, 

 was no proof of the general health of the insect, as tlie mala- 

 dies affected rather the quantity produced, and the present great 

 fineness was due likewise to the dii^sase." (rroceedings of the 

 Entomological Society of London.) The silk-worm is an an- 

 nual, though some species of this group yield two and three 

 broods in the warmer parts of India. It moults four times, but 

 occasionally only three times. 



The cocoon of the silk-worm is white or whitish j'ellow and 

 is over an inch long and nearly half as broad ; 3G0 cocoons 

 weigh a pound and a half. In France and Italy about thirty- 

 six days elapse between the hatching of the larva and the for- 

 mation of the cocoon, it taking four da^-s for the spinning of 

 the cocoon. In England and certain parts of India it requires 

 forty-six days for its formation. 



The above remarks apply to Bombyx mori Linn., the Chinese 

 silk-worm, which feeds on the mulberry, originally derived from 

 the mountainous provinces of China. It is the largest and 

 strongest of the domesticated species. There are, however, as 

 shown by Captain Hutton, twelve species of silk-worms, most 

 of which have been confounded nnder the name of B. mori., 

 and which belong to the genera Bomhyx of Schrank, Ocinara 

 of Walker, and Trilodia Moore. There are six domesticated 

 species of Bombyx. There is not silk enough in the cocoon 

 of Ocinara to make it worth cultivating (Hutton). 



Captain Hutton, speaking of the larvae of B. Hiittoni, re- 

 marks that it "is curious to observe the instinctive knowledge 

 which these worms appear to possess of the approach of a hail- 

 storm. No sooner are the peals of thunder heard, than the 

 whole brood seems to regard them as a warning trumpet-call, 

 and all are instantly in motion, seeking shelter beneath the 

 tliicker branches, and even descending the trunk of the tree to 

 some little distance, but never proceeding so low down as to 



