948 Marvels of the Universe 
feeding. Taking hold with the six true legs and the few central claspers, the hinder third of the 
body is without any apparent claspers, and is generally held aloof over the back or sticking straight 
out ; at other times holding on the edge by its front legs it will curl up the other part into a 
perfect coil, and then much resembles a flat-coiled snail shell. 
These characteristic poses of the Saw-fly grubs will always distinguish them from those of butter- 
flies and moths. 
Another common character is the number of black spots on each division of the body, and two 
very prominent ones on the head. 
It is amusing and quite startling at times, when passing a large brood of Saw-fly caterpillars, 
to note how, directly one’s shadow falls upon 
them, they all start wagging their tails in the 
most vigorous manner. 
When full grown, and some attain to this 
condition in a fortnight or three weeks, the 
caterpillars leave their food-plant and solemnly 
walk down the twigs and branches and 
trunk, until they reach the ground, into 
which they laboriously burrow a short depth, 
and by twisting and twirling their bodies 
about, form a small oval chamber. They 
then line this with coarse silk, and resting for 
two or three days upon their back, change 
to pupe—the perfect Saw-fly emerging 
sometimes the same year, while others  re- 
main till the spring. 
The greater number of Saw-fly grubs 
form these subterranean cocoons ; but others, 
and among this series we find the largest 
species—the giants of the family—are in- 
ternal feeders. 
On page 887 is a photograph, natural size, 
of one which lays its eggs on the pine-tree 
trunks, into which the grub eats a_ hole, 
feeding upon the solid wood, until it reaches 
[By Fred Enock, F.L.S. 
THE WILLOW SAW-FLY. full growthin a year or two—during that 
Here the Fly has laid an egg in the lower Willow-leaf, where : : oN 9 x : 5 
= & 1 
the ruddy-coloured gall has already formed. The Fly cuts a minute time it 1s boring I oles, larger and larger, 
slit in the leaf, therein lays an egg, then with a special saliva until they are from a quarter to nearly three- 
isd the Jon af Menton whichis s Mesthares deuieeeine eighths of an inch im diameter. They form 
a blister or gall. their cocoon of the small pieces bitten from 
the burrows and close up to the bark. In July or August the matured insect bites a hole through 
the hard cocoon and bark and emerges, resting on the trunk until its beautiful wings and 
steel-blue body are fully developed, and then taking its flight. The noise of its powerful wings 
in motion is considerable, and it is often an object of terror to those who see it and imagine it to 
be a hornet. 
Another large species affects the willow, while a still larger one is often found on the hawthorn. 
The caterpillar feeds at night, and is a conspicuous object when the light of a lantern is thrown on 
it—the whole body is almost pure white, on a delicate green ground. This one appears in April, 
and, when caught, exhibits tremendous power in its jaws, which it uses in self-defence on the fingers 
of its captor. The hard, oval cocoons may frequently be seen in the winter on the bare twigs 
