■I'llK MKANlN(i AND I'SE oK 'I'lll': Cttl.orK AND I'OK.M ol' INSECTS. 23 
an acute anj^lc with tlie main stem — without some means of support. 
Anyone can satisfy himself on that point hy holding out his arm from 
his hody, when ho will find how soon the muscles will tire. Nature has 
therefore provided this caterpillar with the power of spinning for itself a 
very fine silken thread, one end of which it attaches to the twig and the 
other end to its mouth, and in that way the caterpillar maintains its 
position for any length of time it pleases. 
The next illustration is another very interesting example of protective 
resemblance. It is that of the caterpillar of the Brimstone moth on the 
Hawthorn tree. Here the harmony of colour is as perfect as is the 
resemblance to the form and shape of the twig. Many of the smaller 
branches of the tree are bent similarly to the attitude assumed by the 
insect, and at the curve in the branch there is a slight projection which 
is exactly reproduced in the caterpillar. It is moreover a noteworthy 
fact that this caterpillar can adjust its colour according to its surround- 
ings. At one time of the year, when feeding upon the young green leaves, 
it is greenish in hue, whilst when feeding upon the older leaves it becomes 
of a brown colour. Altogether this is one of the most perfect forms of 
protective resemblance that is known amongst this class of insects. 
Another interesting example is the caterpillar of the large Emerald 
moth, which, curiously enough, imitates the catkin of the Hazel or Birch on 
which it feeds instead of the branch of the tree. Here you see it before you 
short and thick, harmonising in colour as well as in form with the catkin. 
The rings of its body likewise resemble the overlapping scales of the 
catkin, while its head is well bent forward, making itself look much more 
like an eccentric vegetable growth than a living insect. 
In all the cases we have thus far examined, the caterpillars make 
themselves harmonise with their surroundings ; but there are some which 
act differently, though having the same object in view, and make their 
surroundings resemble themselves. This is the case with the caterpillar 
now before us. When feeding, it ingeniously eats away portions of the 
leaf, leaving rough models of itself near the midrib, and then sits down 
beside it. Here is the caterpillar — green above and dark beneath — 
harmonising well with its surroundings, whilst the irregular pieces of 
leaf which are rejected by it when feeding draw one's eye away from it 
rather than towards it. 
We have noticed instances of caterpillars imitating twigs or branches 
and others imitating the catkin or blossom of a tree. Oar next illustra- 
tion is that of a spider imitating the lichen on a tree. Here it is lying 
flat against the lichen, and it will be noticed that that part of its body 
which is similarly coloured to the lichen it places against the lichen, and 
that part of its body which is coloured brown it places against the bark 
of the tree. 
Our next picture represents an insect (another spider, a native of 
South America) imitating a knot of a tree. Unlike the method adopted 
by the former spider, it stands prominently out on a large branch of a 
tree, and by drawing itself well together it succeeds most admirably in 
making itself look much more like a knot on the tree than an insect, and 
in this deception it is greatly aided by its being protectively coloured. 
Another very interesting case (also from South America) is a 
