ANATOMY AND PHYSIOLOGY 
SI 
extremity of the hair. Bulbous tenent hairs occur also on the 
tarsi of Collembola, Aphididz and other insects. 
Nettling hairs or spines clothe the 
caterpillars of certain Saturniidz 
(Automens), Liparide, etc. ‘These 
spines (Fig. 99), which are sharp, 
brittle and filled with poison, break 
to pieces when the insect is handled 
and cause a cutaneous irritation 
much like that made by nettles. In 
Lagoa crispata (Fig. 100) the irri- 
tating fluid is secreted, as is usual, 
by several large hypodermal cells 
attae base ot each’ spine. These 
irritating hairs protect their pos- ~ g 
‘sessors from almost all birds except 
Fic. 99. 
S 
cuckoos. 
Repellent Glands.—The various 
Stinging hair of a caterpillar, 
Gastropacha. c, cuticula;  g, 
gland cell; h, hair; hy, hypo- 
dermis.—After CLAus. 
offensive fluids emitted by insects 
are also a highly effective means of defence against birds 
and other insectivorous vertebrates as well as against preda- 
Fic. 100. 
Stinging spines of a 
caterpillar, Lagoa _ cris- 
pata.—After PACKARD. 
ceous insects. The blood itself serves 
as a repellent fluid in the oil-beetles 
(Meloidz) and Coccinellide, issuing as 
a yellow fluid from a pore at the end 
of the femur. The blood of Meloidz 
(one species of which is still used me- 
dicinally under the name of “ Spanish 
Fly”) contains cantharidine, an ex- 
tremely caustic substance, which is an 
almost perfect protection against birds, 
reptiles and predaceous insects. Coccinel- 
lidee and Lampyride.are similarly exempt 
from attack. Larve of Cimbex when 
disturbed squirt jets of a watery fluid 
from glands opening above the spiracles. Many Carabidee 
eject a pungent and often corrosive fluid from a pair of anal 
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