388 Dr. Wallace on the Oak-feeding 
June Ist. One larva moulted for the second time. I had to help 
this larva and also another, which was moulting for the first time, 
by shifiing the old skin off the last two or three segments by 
means of a fine-pointed pair of forceps. This operation becomes 
necessary when the hind claspers have lost their grip of the silken 
threads attached to the leaf, and there is no longer any back-hold 
by means of which the larva can crawl out of his own skin. He 
is able, by means of alternate extensions and contractions of the 
segments of the body, to slip off the skin up to the hinder seg- 
ments; but to get those parts free of the skin the feet require to 
be attached to the leaf, and he then crawls out, leaving the skin 
behind. [tis often necessary, in rearing larve, to help them 
when by any accident their hind feet have lost their grip; and it 
is effected very easily by laying hold of the old skin by a pair of 
pointed forceps, and slipping it over the anus. This must be 
done carefully, so as not to injure the tender claspers, and patience 
is needed to watch the moment when the larva elevates his hind 
feet. In withdrawing the skin, care must then also be taken 
to withdraw the lining membrane not only of the last pair of 
spiracles, but also of the intestinal tube. I have in this way fre- 
quently operated with success both on Azlanthus and the Yama- 
mai larve, holding them gently between the forefinger and thumb 
of the left hand. But the skin of the Yamamai is much thinner 
and more easily ruptured than that of B. Cynthia ;* and whereas 
I have often, in half-grown and large larvee of Cynthia, removed 
successfully the old skin, slipping it over the whole body, yet such 
a proceeding is quite impossible with the Yamamaz, on account 
of the thinness of the membrane. And further, I have observed 
this difference, that the Cynthza larva fixes itself more tightly to 
the leaf, and if accidentally detached, is quite unable to lay hold 
again, chiefly because the silken threads, being separated from the 
leaf, are entangled in the hind claspers ; whereas, in the Yama- 
mai, | have seen the larva refix his grasp on the leaf successfully 
almost up to the moment of change, so that fortunately there is 
less fear of losing them from the accident by which so many larve 
of Cynthia are lost, viz. by their losing their hold while moulting. 
June 2nd. Many moulting ; one dead ; temperature rising 60° 
—70°. 
June 5th. Ten have moulted for the second time; counted 
ninety-five alive. 
* Tf a hole is once made in the skin, it is certain death; a ereen fluid 
exudes freely, the larva shrinks and soon dies, 
