PEAR LYDA} SOCIAL PEAR SAWELY. 1238 
together in their web, but reached out from it to feed on the Pear- 
leaves, which they greedily devoured, starting at the edge, and made 
great havoc with. In one instance they had eaten away about 
two-thirds of a leaf up to the mid-rib, leaving only part of some of 
the chief side veins. 
The spinning powers of the caterpillars were very noticeable in 
endeavouring to reconstruct a shelter for themselves when a Pear- 
leaf, which had partly covered over a large party of them, had been 
removed. 
On July 21st Mrs. McQuoid, a friend and neighbour, mentioned 
to me having observed a web-nest, estimated at about three inches 
across, on a Pear tree in her garden in Romelands, St. Albans. This 
contained about fifty shining, reddish orange, ‘‘ worm-like” cater- 
pillars, which were doing so much damage that the nest had been cut 
off and destroyed before I heard of it; but from the description 
(though without personal inspection) I do not think it could be other 
than one of the social collections of caterpillars of Lyda pyri. 
I have not had the opportunity of tracing the whole life-history of 
this Pear Lyda, but taking the main points from the writings of the 
late Prof. Westwood, Schmidberger, and Taschenberg, it is as follows. 
The female Sawfly lays (towards the end of May) from forty to 
sixty eggs, mostly on the under side of the Pear-leaves. These eggs 
are longish in shape, yellow, and look as if smeared with grease, and 
are laid with great regularity in rows. The caterpillars, which hatch 
out in a few days, are at first of a whitish yellow colour, but become 
darker after the first moult, and begin immediately to spin a loose 
web, in the threads of which they climb to and fro. This web is 
enlarged, as requisite consequently on the ragged and filthy condition 
which it acquires, or to enlarge the feeding-ground, and the caterpillars 
drag themselves about within it by holding on to the threads, and in 
four or five weeks attain their full growth. 
They then let themselves down to the ground, and bury themselves 
as much (it is said) as four inches deep, or deeper still, in the earth, 
in a smoothed cavity, but without spinning a cocoon. Here they 
change to the perfect Sawfly, which, according to recorded observations, 
may appear in the following spring, or in the spring next but one to 
date of going into the ground. 
Various observers have mentioned difficulty in rearing this Sawfly 
in artificial circumstances, and perhaps the following plan, which I 
have found answer well, though I have not tried it with this special 
infestation, might help those who wish to observe the life-history of 
this somewhat rare attack. I took a wire or pierced metal dish-cover, 
such as is used for preventing flies getting at meat in larders, and 
placed this on the ground where the larve had buried themselves of 
