Proceedings NG 
later stages. The case is built of the dung of the caterpillar, 
which instead of being cylindrical as in most caterpillars is in 
the shape of flat bricks, admirably suited for the purpose. As the 
caterpillar grows the case has to be enlarged, and this is done as 
follows:—The caterpillar, starting at one end close to the open- 
ing, attaches pieces of the excrement by one edge to the case 
with silk and gum; the edges of the new work are brought 
gradually back about two thirds of the length of the case and 
curved inwards till the two sides meet in an arch; the portion 
of the case inside the new work is now cut away and the enlarged 
case is ready for the increase in size of the caterpillar; the ad- 
ditions are made alternately at opposite ends of the case. The 
walls are made beautifully smooth both inside and out with silk 
and gum, and are so strong that it is quite impossible to crush 
them between the thumb and finger. The caterpillar spends hours 
of his ‘spare time’ in going over the outside of the case with silk, 
until all vestiges of the separate bricks are lost and the surface 
is perfectly smooth. 
When about to pupate the caterpillar fixes the case in a ver- 
tical position to a twig by the lower end, the upper opening 
being thus protected from wet by the turned up end of the case, 
and any water that may possibly get into the case will escape by 
the lower end, so that there is no possibility of flooding the inside, 
as might happen if it was fixed horizontally. 
A well known protective habit in caterpillars, common in 
many of the Voctwidae, is to bury themselves during the daytime 
in the ground, issuing at night to feed. 
But I will now come to what we may call Weapons of De- 
fence in Caterpillars. 
Many caterpillars are protected by special odours which we 
may well believe to be disagreeable to their enemies, though we 
must be on our guard against assuming that an odour offensive 
to man is necessarily so to other animals. 
A good example of protection by an offensive odour I have 
observed in the caterpillar of Morpho laertes. This is a very 
beautiful and brightly coloured caterpillar, a conspicuous object 
at any time, but especially so when hanging in a cluster of a 
dozen or so to a leaf of the tree on which they feed, which is 
