275 



depends upou the size of the jaws, we see that au occasional cbangfe is 

 necessary to meet the requirements of an increasing appetite. Wlieu 

 reared under cover, the leaves must be occasionally sprinkled in order 

 to supply the worm with drink. 



In a short time after the first molt it becomes somewhat darker in 

 color and in ten days prepares, as before, for the second molt. It has 

 then reached a length of about 26""". At the twenty-first day it makes 

 a third cast of the skin. Its length is 45™"'. 



Just before the fourth molt, which occurs near the thirty-first day, it 

 measures 70™"^. This is its final caterpillar skin. The head which 

 was previously more or less tinted with red remains of a permanent 

 green. The sides are adorned with metallic silver si)Ots, and other 

 less conspicuous markings. 



The fully grown worm forty-seven days after hatching from the egg 

 is of a length of 90""" or 100""". It is then about to produce the cocoon. 



The fully grown caterpillar wanders about the branches of the Oak evac- 

 uating from its bowels, not the hard dry i)ieces characteristic of its ordi- 

 nary condition, but a soft semi-fluid matter which will inar any cocoon 

 upon Avhich it happens to fall. For this reason, as well as to avoid ac- 

 cidents consequent upon being disturbed, the twigs containing spinning 

 insects should be removed from the neighborhood of those preparing 

 to spin. The worm generally selects a spot where two leaves can be 

 drawn together to afford a partial shelter. Between these leaves it en- 

 sconces itself. 



The first silk thrown out is of a golden-green color. With this is 

 covered the stems of the leaves, the twig from which they grow, and 

 also their proximal surfaces. This silk forms a sort of scaffolding. It 

 ])revents the leaves, and with it the web, from failing off" the tree, de- 

 fines the space that the cocoon is to occu])y and by its color serves as a 

 disguise for the white material that is produced later. Having in- 

 closed itself within this coarse structure the cocoon proper is made. 

 Along the exposed space in the o])ening between the leaves is woven 

 the first thick layer of silk. The head is moved rapidly back and forth 

 across this surface leaving after it its sticky filament. The fiber is laid 

 in loops as if by a flourish of the pen. The entire fabric is comj^osed 

 of a repetition of loops like flourishes. 



Each cocoon, it is stated, consists of a single thread extending from 

 the stem through intricate weavings till it ends upon the inner surface. 

 This thread is from 800"' to 1,000"' in length and .02^"^"' to .05"'"' in thick- 

 ness. 



In a day or two the cocoon is completed. It is a regular oval about 

 50'"'" by 25"'"'. The exposed portions of the outer surface of a golden 

 green, while the portions protected by the leaves are of a pale green. 

 The interior is of a silvery white. 



On the third day after commencing the spinning there is evacuated a 

 milky-white secretion, which permeates the whole structure and in dry- 

 18578— No. 9—2 



