112 CRABS AND INSECTS. 
held in place by a hook, that when released 
sends them high into the air. A single Po- 
dura will deposit 1,360 eggs. The glacier-flea 
(Fig. 133), found upon the glaciers of Europe 
and on snow-banks of North America and 
Europe, belongs to the order. Some species 
have bristles instead of springs, as the Cam- 
podea, found under stones and old wood. 
Order II. Lace-Winged Insects (WVeu- 
roptera).— General Characteristics. — Insects 
having four fine net-veined wings, generally 
Be gre a long, slender abdomen, and mouth adapted 
italia for biting. 
May-Flies (Zp/emera).—These remark- 
able insects are of a greenish-brown color, with gauze-like 
unequal wings dotted with brown spots. The larva (Fig. 
134) is about an inch long, its sides bearing several plume- 
like gills by which it breathes in the water. 
efte 
VALUE.—In some countries they occur in such numbers that they 
are used as guano. The Central Africans make bread of them. 
Dragon-Flies (Litelulide).—The darning-needles 
(Fig. 135) are adorned with lustrous metallic tints and 
jace-like wings. The abdomen is long and bears no sting; 
the eyes are compound and accompanied by three ocelli. 
The eggs are deposited in the water, and are hatched into 
flattened larve (Fig. 135, 2) that lead an aquatic life for 
about two years. They secure their prey with a proboscis 
with hooks and joint that when at rest folds over the face 
and is called the mask, m. The pupa, 4, finally creeps 
up the stem of a plant, bursts from its old skin, and ap- 
pears a perfect insect, c.* 
*In Lombok, Malay Archipelago, the natives catch the large 
species and eat them. The American species are voracious; the larvz 
catch young fish, and the adult has been seen to take minnows from 
a pond, 
