THE TENTHREDINIDE.. 167 
distinguishable on account of the movable, dentate, saw-like 
ovipositor which is attached to the abdomen of the females. 
This is a wonderful little instrument. It is in the form of 
a double saw, the length of which varies according to the species, 
and there are from fifteen to twenty or more regularly placed teeth 
added to the cutting edge. But the little saw of the Zenthredo is 
not always so simple in its construction as that of a carpenter, 
for the teeth or dentations are covered with others, so that 
the teeth of the saw are themselves toothed. The perfection 
of this minute weapon suggests that manufacturers might take 
a lesson from it and invent a cutting saw with double serrations, 
which might be of infinite use in the arts. 
The double saw corresponds to the stylets of the sting of the 
wasp and bee. The two valves are kept fixed by being inserted 
or fixed into a scale which adheres to the sides of the abdomen ; 
and the process that surrounds the stylets of the sting may be 
noticed in its rudimentary condition as a thin membrane in the 
saw-flies, but it is of no importance to them. 
The Tenthredinide have active dispositions, and are orna- 
mented with various colours, and their bodies are smooth and 
shining. They do not consume much nourishment in the adult 
stage, and they then appear to prefer fruit, which they snip in 
pieces with the aid of their cutting mandibles. 
The larve resemble caterpillars in their shape and habits, yet 
it is hardly possible for any one to mistake them for the miniature 
form of the Lepidoptera. It is true that amateur entomologists 
have nourished and taken vast pains with the larve, believing 
that they would eventually turn to new and splendid butterflies, 
and that they have been surprised at the evolution of a saw-fly 
instead of the expected scale-winged insect. But in spite of 
the resemblance, the mistake ought never to occur if a careful 
examination be made. 
Caterpillars have never more than five pairs of membranous 
or hind legs, but the larve of the saw-flies have generally seven 
or eight, and never less than six pairs. The feet have, however, 
circles of hooks, like the caterpillars. The head is always rounder 
and more globular, and the eyes are more wide apart and distinct, 
than in the larve of the butterflies. The saw-fly larvae have, 
