THE TENTHREDITES . 
175 
The females lay their eggs by inserting them with their saw- 
ovipositor between the skin or cuticle of the turnip leaf and its 
cellular or parenchymatous structure. The egg is therefore only 
separated from the atmosphere by a most delicate membrane, 
so that the heat and moisture soon affect it and hatch the little 
Athalia centifolice very rapidly. It appears necessary that this 
egg should be exposed to much heat in order to hasten the birth 
in time for the turnip to be enjoyed by the larva. Newport 
states that the cocoon of this insect is lined with silk. 
The larvae of the genus Selandria are of a somewhat peculiar 
shape. Their legs are extremely short, and their bodies are lubri- 
cated with a viscid secretion which makes them look like small 
slugs. Reaumur, in fact, called them slug larvae. The larvae of 
Selandria AEthiops often become very injurious to cherry, pear, 
Lophyrus pini. 
and other fruit trees. They remain perfectly quiet during the 
heat of the day, and seem to draw their heads within the first 
segment of their bodies, and they are then covered over with 
the slimy moisture so as not to look like insects at all. By 
night and during the early morning they are lively enough, 
and they then devour the foliage. 
The Lydites form a small group of saw-flies which are charac- 
terised by having a great number of joints to their antennae. They 
are the saw-flies of the north, and they attack fir trees and pines. 
The Lophyri , which belong to this group, have a thick body, 
and the males have doubly pectinated and feathery antennae. The 
species are very difficult to separate, and entomologists have had 
to take into consideration the disposition of the nervures of the 
wings, in order to decide upon particular forms with certainty. 
The commonest species is Lophyrus pini . The male is quite 
