PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NAT UR AT, SCIENCE. 
107 
years residing in the neighbourhood. When an insect 
possesses any protection sufficient to meet the dangers to 
which it is exposed, we find no other is exerted in that 
direction ; and whenever bright colours are not dangerous 
to an insect, they are often profusely given. 
With this digression, I now come to the subject we have 
mmediately in hand. Everyone is aware that bees and 
wasps are often of bright and gay colours, but they have a 
wonderful protection in their stings, and on that account 
receive all due respect from their neighbours. But although 
these formidable tribes are so strongly armed, they too 
have their enemies in the shape of some parasitic flies of 
the genus Volucella. These have no stings or offensive 
iveapons of any kind with which to wage war against 
their stinging hosts. Their modes of operation are of 
a more subtle nature, for they mimic so closely, by their 
colours and general appearance, the bees and wasps upon 
which they prey, that they can enter the nest unmolested, 
as members of the community, and, having gained ad¬ 
mittance, deposit their eggs in the larvae, thus sowing the 
seeds of destruction in the nest, and also fulfilling their 
mission of providing for their progeny, by placing them in 
circumstances necessary to their development. Yon will 
find some specimens of the genus Volucella in the Museum, 
and can see how easily they would be mistaken for humble 
bees. We are told that “ a man’s enemies are often those 
of his own house.” This is, I think, very true of humble 
bees, taken altogether as an order, for there are parasitic 
humble bees which closely resemble in appearance other 
humble bees in whose nests they are reared. Among saw- 
flies we find that many, on the approach of danger, mimic 
or feign death. Tucking their antennae, legs, and wings 
close to their bodies, they fall to the ground until the 
danger is gone. As insects pass through various stages 
before attaining their perfect form, they are exposed to, 
and therefore require protection from, danger during every 
period ; and so the principal means of defence of the saw- 
flies, while in the larval state, consists in the power to 
eject liquids, or the discharge of obnoxious odours. The 
liquids are often of an acid nature, and can be thrown to 
considerable distances. The larvse of one species ( Perga 
Lewesii) discharge a gummy matter, the use of which 
is often clearly shown when an ichneumon, which 
preys upon this species, is found in the secretion, 
having its legs and wings firmly gummed together. 
In most cases where secretions or fetid odours are 
discharged the larvae are of Bright colours and gregari¬ 
ous in their habits, several feeding on the same leaf. 
Among the orthopterous order the same phenomena are 
to be observed. Anyone who has tried to find a grass¬ 
hopper among the grass or low herbage knows what a pro 
tection its colouring affords it, but when we examine the 
genera Mantidce and Phasmidce, or the leaf and stick insects 
and spectres, the imitation existing between these iusects 
and the vegetable world becomes truly alarming. Their 
legs are made to resemble leaf-stalks, the body being elon¬ 
gated and notched so as to imitate a twig, and the large 
wings are exact imitations in colour and neuration of a 
full-blown leaf. There is a specimen of phasma in the 
British Museum which, perhaps, eclipses even these, for 
the wings are covered with spots and blotches, giving it 
the appearance of vegetation marred by the ravages of in¬ 
sects. You will see a specimen of the stick insect in the 
Museum. Mr Belt, in his most interesting book, The 
Naturalist in Nicaragua, gives a most curious case where 
a species of the green leaf-like locust (and here, I think, 
we have a case of reason or conscious instinct) added to its 
protective colouring by its action. It was suddenly sur¬ 
rounded by a large number of the insect-eating ants. From 
this dilemma it could easily have escaped by taking to 
flight, but would then roost likely have been pounced upon 
by the insectivorous birds which usually follow the ants ; 
and, seeming instinctively to know this, it just remained 
stationary among the insect host, trusting to its protective 
appearance, which happily did not fail it, and the ants, 
many of which passed over its body, pursued their journey, 
unconscious that they had been so near a good meal, or had 
been so easily deceived. The aphides, to whose remark¬ 
able power of multiplication I have referred, happily have 
many enemies. I shall mention two that are rather re¬ 
markable, which prey upon them—namely, the larvae of 
Chrysopa and Hemerobius, belonging to the order Neurop- 
tera. These, after extracting the nutritive moisture of the 
aphides, have the most curious habit of arraying them¬ 
selves in the skins of their victims, piling one on after 
another until they are partially concealed. Whether they 
derive any advantage from this practice I have not seen 
stated, but I am inclined to think they must do so by 
being able the more easily to approach and seize their prey. 
Many beetles receive freedom from attack on account of 
their elytra or wing-cases being very hard; others, again, 
have the power to emit obnoxious odours. The pretty and 
brightly-coloured Ladybirds (Coccinellidce) discharge a fluid 
of a very disagreeable nature, and it is probably on this 
account that they are never eaten by birds. The Dung Chafer 
Beetles, on the approach of danger, feign death, and it is 
said that they thereby deceive the rooks, as these birds will 
only eat them when alive. The ever-famous Bornba- 
dier Beetles strike terror among their enemies by the 
sound which they can make, as of an explosion, aecom- 
