112 



CRABS AND INSECTS. 



FIG. 134. 

 Larva of 

 Ephemera. 



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 (Neu- 

 roptera). General Characteristics. Insects 

 having four fine net-veined wings, generally 

 a long, slender abdomen, and mouth adapted 

 for biting. 



May-Flies {Ephemera}. 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. 



VALUE. In some countries they occur in such numbers that they 

 are used as guano. The Central Africans make bread of them. 



Dragon-Flies (LibeUvUda). The darning-needles 

 (Fig. 135) are adorned with lustrous metallic tints and 

 iace-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 larvae (Fig. 135, a) 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, b, 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 larvae 

 catch young fish, and the adult has been seen to take minnows from 

 a pond. 



