THE STATE ENTOMOLOGIST. 8.> 



There is one race known as Atmual which will not produce more than 

 one brood each year, no matter how the egiis are manipulated; another 

 known as Bivoltin which produces two broods a year; and a third (Trevoltm). 

 which produces three annual generations. Yet by changed conditions each 

 of these races can, in a few years, be rendered inconstant and variable in 

 these particular characteristics. There are races (and they are more especi- 

 ally adapted to warm countries) such as that of Milan, and most of the 

 Trevoltins, which, habitually moult but three times; and it is evident that 

 even this important diifcrencc has been artificially produced, since ordinary 

 worms occasionally moult but three times and the three-moulters or races <i 

 trois mueSj as the French call them, sometimes moult four times.* 



The Mulberry silkworm is, when compared to other insects, an 

 anomaly. It had already been so long under the influence of human man- 

 agement ere it was introduced into Europe, that we find the larva, when full 

 grown, possessing the white color so tyjHcal of domestication ; which is the 

 more remarkable that w^hite is extremely rare in Lepidopterous larva?, and 

 unknown in any of the external feeders belonging to the Silkworm Family 

 (Bombycidce). That this lack of color is the direct result of domestication, 

 as in so many other animals, maj^ be very justly inferred, because when 

 newly born the worm is almost black, and in the older worms there are con- 

 stantly appearing individuals with dark or tiger-like marks w^hich have been 

 attributed to reversion by Captain Hutton, who, by separating and breed- 

 ing from them, found that in the third generation they had become darker 

 and that their moths were likewise darker, and resembled in coloring the 

 wild Huttoni of Westwood.f We find furthermore, that it has lost all desire 

 of escape,^ and the worm wall seldom crawl out of the shallow^est tray so 

 long as it is supplied with food, while the moth is equally contented t«> 

 remain in the same trays. So thoroughly has it lost all instinct of self 

 preservation that, as we learn from good authority, when placed upon a tree 

 out of doors, the worm is easily blown down by the agitation of the wind, 

 and not unfrequently commits the blunder of severing the petiole of the 

 leaf upon -which it rests, and thus unconsciously brings itself to the ground 

 from which it seldom has the tact or power to rise again. We find also, 

 that the moth has lost almost all traces of color and very nearly all j)Ower 

 of flight; its wings scarcely ever expand much beyond the length of the 

 cocoon, from which it issues, while most of the wild silkworms, (take, for 

 instance, the Polyphemus, iigures 50 and 53,) expand from four to five times 

 the length of their cocoons. The male flutters a little, but the female can- 

 not rise off her feet, and never makes the attempt; yet there is everj' reason 

 to believe that they both flew in the wild state, and it has been shoAvn that 

 after three generations reared in the open air, the males recover in great 

 part the lost power. 



* See Darwin's Animals ami Plants, etc., p. 302. 



t Trans. Lond. Ent. Soc. 3ril Serie-;, Vol. !^, pp. 15'', 308. 



