7i 
third kind have bright, metallic green bodies. The one in our 
illustrations (Enallagma cyathigcrum) has a bright blue body 
ringed at intervals with dark brown. 
Great Diving Water Beetle. — This insect is very commonly 
met with while pond hunting. Its colour is a deep, brilliant green 
on the back and glossy brown beneath. As its specific name implies, 
a margin of yellow outlines the dorsal surface. The sexes may be 
distinguished easily, for the back of the male is quite smooth, while 
that of the female is longitudinally grooved. These insects are, if 
possible, more predaceous than the Water Boatman, readily devour- 
ing tadpoles, newts, and all the soft-bodied creatures which share 
their haunts. Should this food run short they will devour one 
another with avidity. Like many other aquatic insects, they are 
surface breathers, rising regularly to replenish their stock of air. 
This is carried between the wings and body, and experiments made 
on one of these creatures showed that the air so contained will last 
them for an hour or more. The larva is a very curious object, quite 
unlike the perfect insect. It is as transparent as a shrimp and is 
not at all unlike one at first sight. It is very voracious, its appetite 
being almost insatiable. As it is rather a weak swimmer it prefers 
to crawl about over the mud and capture its unwary victims by 
stealth Its colour is so mud like that the victim's first intimation 
of its proximity is the snap of the sickle-like jaws across its body. 
These jaws are hollow throughout and have tiny orifices at their 
tips. Through these holes the juices of the prey are sucked till 
little remains of it besides the horny covering. Towards the end of 
July the larva, which has hitherto breathed from the surface through 
its tail, quits the water and burrows into the soft mud well above the 
water line. After working itself round and round for some hours an 
oval chamber is formed, and at the bottom of this the exhausted 
creature lies upon its back. Gradually' its length shrinks, till after 
about a week the skin splits down the shoulders, and with much 
wriggling the old skin is cast off, leaving a quiescent pupa. This is 
quite white, and has the wing and leg cases standing out from the 
body — not fused smoothly together, as in the case of chrysalides of 
moths and butterflies. After some three or four weeks the skin at 
the back again splits, and this time the perfect beetle emerges. 
Silver Water Beetle. — This insect is not nearly so common as 
the one last described, but in some neighbourhoods it seems very 
plentiful. Unlike the Diving Beetle, it subsists entirely upon pond 
weeds, and may be safely kept in aquaria with fishes without fear of 
its attacking them. Rather larger than D. marginalis it is of a 
deep olive green on the back, while the under surface is given a 
yellowish-brown appearance by a dense covering of short hairs. 
These bristles, as in the case of the aquatic spiders, prevent the 
water wetting the under surface of the insect, and so carry’ a supply 
of air on which the creature draws whilst submerged. When below 
the surface the under parts of this beetle have a very silvery appear- 
ance. If our illustrations of the two beetles be consulted it will be 
readily seen that D. marginalis has specially-developed oar-like 
legs which carry it rapidly through the water, while H. pice us has 
legs like any terrestrial beetle, and consequently its swimming is 
somewhat slow and laboured compared with that of the diving 
beetles. The larva of this species is very similar in appearance to 
that of D. marginalis and quite as voracious, feeding on any soft- 
bodied animals which it can capture. The pupa, too, is similar to 
that of the last-named beetle, but the eggs of H. piceus are enclosed 
in a hard cocoon which is fixed to a submerged plant. 
