MOTH. SILK-WORM. 411 



which may probably compensate for the want of others which our 

 climate has denied us. 



Yet our climate itself is in some respects superior to those where 

 silk is raised. In the south of France the frosts are often so in- 

 tense as to kill the mulberry leaves after they are out. At that 

 season of the year, this is seldom the case in England ; which is 

 also more free from lightning, and those sultry heats that have 

 always been deemed prejudicial to the silk-worm. From such 

 considerations, the time may perhaps arrive when our countrymen, 

 by farther knowledge and experience, may be enabled to avail 

 themselves of these exclusive advantages, and become entitled to a 

 rank as distinguished among the raisers, as that which they have 

 long held among the manufacturers of silk. 



The silk-worm, however, is far from being the only insect of 

 whose labours man might probably avail himself. There are many 

 species very common, and immensely fertile, that might be bene- 

 ficially employed in procuring silk, did we know how to profit of 

 their labours. M. de Reaumur has mentioned several whose pro- 

 ductions deserve a trial, although we are aware that the silk of 

 many of them is altogether unfit for our purposes ; their coques 

 being not only coarse, but so scantily provided with silk, that the 

 animal is obliged to join dry leaves, bits of wood, and other 

 materials, in order to give stability to its edifice. Some of them 

 indeed spin under ground, and their work consists only of joining 

 and connecting together, by means of their threads, different par- 

 ticles of earth, of which their house is composed. These cater- 

 pillars, when kept by the naturalist, who waits for their perfect 

 form, must be supplied with earth in the boxes in which they are 

 lodged ; otherwise they will perish, from not being able to con- 

 struct an edifice fit for their reception. 



The moths differ from the butterflies, in remaining in their chry- 

 salid state for a much longer period before their metamorphoses 

 into perfect insects are completed. Their form, too, is then differ- 

 ent, being oblong, and not angular, like the chrysalid of the 

 butterfly. Some remain in their coques for several years succes- 

 sively ; especially if a cold damp situation have retarded their pro- 

 gress. So great is the effect of heat in precipitating their develop- 

 ments, that a moth in a warm exposure may be produced from its 

 chrysalid, even in the depth of winter. 



