4.0 



F'«' 31- by fastening together a few leaves •with silken 



threads, in the interior of which the larva spins a 

 second strong and very close cocoon in which it 

 changes into the pupa (Fig 32). These cocoonB 

 fall with tlie leaves in the autumn, and remain on 

 the ground during the winter until the perfect 

 insect emerges. The pupa is very thick and short, 

 and shows very clearly the antennae and wings. 

 The larva takes about a week to coraplete its co- 

 eoon. The silk of which the inner one is formed is very j-ie. 32. 



glossy, rather coarser than that of Bromhyx mori, and accord- 

 ing to M. Trouvelot, can be used very extensively in com- 

 merce. It has a continuous thread and can be readil}' unwound. 

 We are not aware what the actual length of the silk in each 

 eocoon amounts to, but it mu.st be something very great, 

 if one may judge it by comparison with that of the Chinese ' 

 silk worm. Rennie, in his Lised Architedure, in speaking 

 of the latter states, " that the length of the unbroken thread in a cocoon varies from 

 six hundred to a thousand feet ; and as it is all spun double by the insect, it will amount 

 to nearly two thousand feet of silk, the whole of which does not weigh above three grains 

 and-a-half ; five pounds of silk from ten thousand cocoons is considerably above the aver- 

 age." When we see the enormous difference in size between the cocoons of Poii/pliemvs and 

 mori, we can well believe that it may be very advantageous to the silk grower, to do all 

 he can towards developing the experiments already made in the culture of our American 

 silk worm. We must not forget, however, that among.st our ornamental and forest trees 

 the larva is capable of doing much harm, and in the present instance we can only regard 

 it as a noxious insect, and therefore one to be destroyed. Like everything else in the 

 insect world, it has its special enemies, being very subject to the attacks of an Ichneumon 

 fly, named Ophion Macrwmm. Hand picking is the only remedy we are aware of 



4. THE CECROPIA EMPEROR CATERPILLAE. (Plalysamia cecropia, Linn.) 



Order, Lepidoptera ; Family Bombycid^. 



This insect was fully described by the Rev. Mr. Bethune, in his treatise on insectB 

 injurious to the Apple, contained in the Commissioner's Report for 1870, to which we refer 

 our readers for further details. As the caterpillar feeds also on maple leaves we have 

 given a figme of it, No. 33. 



Fio. 33. 



Colotuv — Green, bhie, yellow and led. 



Mr. Bethune well describes it as a giant among caterpi 

 long when full grown. ~' 



ars. It is about four inchwr 

 The colour of the body is pale green, and it is covered with tuber- 



