Packard.] 
INSECTS AS MIMICS. 
271 
its back exactly like the leaf scars of the juniper, and the 
entire worm concolorous throughout with the bark is a per¬ 
fect imitation of the twig. 
Nearly every bush has its distinct kind of inch worm or 
geometer, which resembles a broken branch or twig when 
it is at rest and holds itself out stiff by its muscular 
hind legs. Most caterpillars remain quiet by day, when 
they need protection, and feed at night. The stick insect 
(Fig. 209, from Tenney’s Zoology) is so obviously a mimetic 
form that we need only speculate how it came to differ from 
its allied forms, unless the intermediate forms have become 
extinct through the want of similar adaptation. This and 
the celebrated leaf-insect are the two insects which first 
come to mind when the subject of mimicry is mentioned. 
The Phyllium is broad and flat, with leaf-like dilatations on 
the legs, while the broad wings are provided with a midrib 
and vein exactly like a dried leaf. 
Other remarkable stick insects of the group of Phasmids 
are figured by Professor Westwood in his “Thesaurus Ento- 
mologicus Oxoniensis.” Such as the Extatosomci bufonium 
from Australia, Heteropteryx Castelnandii from Tringany, 
Malacca and Ceroys laciniatus from Nicaragua. They are 
much alike in form, though inhabiting different quarters of 
the globe, and are slender, with long legs, with flattened 
tubercles and spiny expansions, resembling the young and 
spiny twigs on which they possibly rest. 
The caterpillars of the leaf-rolling and Tineid moths 
often live in rolled-up leaves, where they are protected 
in a great measure from their enemies; though the insec¬ 
tivorous birds, attracted perhaps by the deformation they 
cause in the foliage, feed upon them; and their insect 
parasites, particularly the minute chalcid flies, have the 
requisite instinct to find them out and oviposit in their 
bodies. No insects, however protected by these disguises, 
are ever thoroughly safe from the attacks of enemies espe- 
15 
