546 
Annual Report of New York 
of the light, looking as though the leaf had there been lightly 
touched with varnish. If nothing occurs to drive it therefrom, this 
spot becomes its residence for a few days. And wherever it takes up 
its abode subsequently, it constructs a similar mat, into the threads 
of which it can catch the minute hooks of its feet, to render its stand¬ 
ing more secure than it is upon the naked surface of the leaves. 
It next begins to feed upon the leaf, some six or twelve hours after 
it lias finished eating the egg shell. At some point slightly outside 
of the edge of the mat on which it is standing, it eats a round hole, 
the size of a small pin head, into which it gradually sinks its head, 
deeper and deeper, until it passes through the parenchyma of the 
leaf to the skin of its upper surface. As yet it is so small that the 
eye only perceives it to be a minute cylindrical pale yellow worm, 
usually lying straight and motionless on the leaf. But as it feeds on 
the green pulp of the leaf, its body acquires a green color and slowly 
increases in size, growing about one-thirtieth of an inch in length 
daily. 
Foreign authors state that in getting its growth this cabbage worm 
molts or casts its skin “ several times.” I can say with perfect confi¬ 
dence, it is only three times that it molts. When it first comes from 
the shell it is extremely soft and its skin admits of much distention 
before it constricts the worm to such a degree that it requires to 
throw it off. It is not till it has grown to double its first size and is 
0.12 to 0.15 long that it casts off its skin the first time. It then 
feeds and grows till it has again doubled its size and is 0.25 to 0.30 
long, when it molts a second time. It again doubles its size and 
becomes about 0.50 long, when it makes its third molt; and the skin 
which it then acquires it retains till it reaches maturity, throwing it 
off only when changing into its pupa form. This is the uniform 
course of these worms, as I have observed in a number of instances. 
The only aberrations I have noticed in these moltiugs are, that one 
of them is sometimes deferred till the worm is much larger; yet this 
does not appear to affect the other moltings of the same worm, for 
these occur as usual. Thus, in one instance the second molting did 
not take place until the worm was 0.38 long; yet the third occurred 
when it was 0.53. In another instance the second molting took place 
when the worm was 0.30 long, yet the third was deferred until it 
was 0.64. 
When the worm is about to change its skin it ceases to feed and 
crawls to a part of the leaf where it will not be liable to be disturbed, 
commonly placiug itself on the upper side of the leaf, frequently in a 
