This larva now proceeded to make itself a case of Alisma plant cujo, 
first securing a piece of leaf that was near, and then fastening this 
under another leaf that floated by ; three hours after it thus hid itself 
I turned the leaf over, and found the piece by this time fashioned 
into a suitable oval shape, and attached to the oval edge of the leaf, 
so that on that side there was no need of cutting: next day the larva 
was shaping the second piece — not merely by cutting a channel, but 
by eating away a large irregular hole outside its case, still, however, 
leaving a narrow isthmus uncut, so as to keep itself securely moored 
for a day or two longer ; but at last when it had to stretch out further 
and further to continue feeding on the leaf it made its case tight, cut 
the mooring, and floated off. AY hen the larva is about to pupate it 
attaches its case at the edge of one side beneath some floating leaf or 
submerged stem, often (as Mr. Jeffrey found a great number) to the 
decumbent stems and tough fibrous roots of the Myosotis bared by 
the action of water, but always fixed edgewise ; indeed, the only 
exception was in a case fixed flat against a piece of Sparganium. 
After the larva had spun up, from seventeen to twenty days 
elapsed before the appearance of the imago; I bred seventeen speci- 
mens in all at intervals from June 21st to August 26th. 
Fortunately for our knowledge of the interesting early part of 
the economy of nymphcealis , Mr. Jeffrey detected amongst some 
Potamogeton natans, gathered promiscuously as food for his larvae, a 
large leaf, having eggs deposited on the under-surface, but without the 
least covering ; and cutting off the extreme tip of the leaf on which 
were six eggs, for himself, most kindly sent me, on 8th of August, the 
rest of the leaf bearing about a hundred eggs of a pale ochreous- 
greenish colour, close together in a dattish mass near the margin from 
which the tip had been severed ; three days later, by aid of a lens, I 
could see tw r o black specks on each egg, and in two more days these 
w r ere distinct enough, and the day after that, August 14th, the larvse 
all hatched, and soon hid themselves by mining into the under-side of the 
leaf not, however, before I had observed and noted their black heads 
and collar plates with pale greenish-yellow translucent bodies. On 
the same day Mr. Jeffrey was watching the six eggs he had retained, 
having placed the severed bit of leaf on the upper surface of a fresh 
gathered leaf put in water ; and at about 8 a.m., saw the little creatures 
leave the egg-shells, and crawl over the upper surface of the fresh 
leaf, and from thence to the under surface, which they at once entered 
by mining on either side of the midrib near the base. In this manner 
mv young brood remained ensconced from thirty hours to three days, 
