NERVE-WINGED OR LACE-WINGED INSECTS 297 
NERVE-WINGED OR LACE-WINGED INSECTS, OR DRAGON-FLIES AND THEIR RELATIVES 
BY THE REV. THEODORE WOOD, F.E.S, 
THE Nerve-winged Insects owe their title to the peculiar character of their wings, the horny 
veins which form the framework of those organs being multiplied and sub-divided to such an 
extent that they assume the appearance of exceedingly delicate network. 
These insects fall naturally into two great groups, in one of which the chrysalis, or pupa, 1s 
active, and continues to take food like the grub, while in the other it is passive and helpless, like 
that of a butterfly or a moth. 
Prominent among the members of the first division are the Dragon-flies, which owe their 
title partly to their extreme voracity, and partly to the fact that they feed entirely upon living 
insects, which they pursue through the air. They are exceedingly swift of wing, and may 
be seen hawking over ponds and streams on any fine day throughout the summer and early 
autumn. 
The earlier part of their lives is spent in the water, in which the eggs are laid by the 
parent insect. The grubs are usually of a dull grey or brownish-green colour, and are remark- 
able for acurious organ known as the “‘ mask,” 
which partly covers the lower surface of the 
head. This apparatus consists of two joints, 
which fold upon one another, but can be ex- 
tended at will, the one farthest from the head 
terminating in a pair of large and powerful 
jaws. When the grub perceives an insect- 
victim, it swims cautiously beneath, and seizes 
it by means of these jaws. The “mask” is 
then folded, and the prisoner drawn down 
within reach of the mandibles, by means of 
which it is speedily devoured. 
The method of swimming practised by 
the dragon-fly grub is also very curious. 
Through the centre of the body runs a 
longitudinal tube, terminating in a circular 
orifice, closed by means of five tightly fitting S 
valves. These valves, which together form a 
sharp spike when closed, can be separated at 
will. When the insect wishes to swim, it 
fills the tube with water, and then squirts DRAGON-FLY 
the contents forcibly out, the result being — These insects are often known as ‘¢ Horse-stingers,”” although they do 
that it is driven swiftly forwards by the i os Bee art el a 
reaction. 
The pupa of the dragon-fly is very much like the grub, with the exception that the 
rudiments of the future wings may be seen on the back. 
About forty species of these insects are found in the British Islands, of which the GREAT 
DRAGON-FLY is a well-known example. The body is 3 inches in length, while the extended 
wings measure about 4 inches from tip to tip. In colour it is light rusty brown, with a 
few pale markings. The “ HORSE-STINGER ” — which is perfectly harmless, notwithstanding its 
popular title —is also common, and may be recognised at once by its flat dull yellow body, 
which becomes blue in the fully developed male. In the graceful and beautiful DEMoisELLE 
the male is deep blue, with black patches on the wings, while the female is entirely green. 
Allied to these insects is the COMMON May-FLY, popularly supposed to live for one day 
only. As a matter of fact, however, it spends a couple of years in the grub and pupa states, 
inhabiting burrows in the banks of ponds and streams. These burrows are curved, and have 
Photo by W. P. Dando, F.Z.S. 
