THE STUDY OF INSECT LIFE 15 



included in the Diptera. While none of the Fleas 

 now have true wings, some possess scale-like 

 plates in the region where the wings of other 

 insects are; and these plates doubtless represent 

 the remnants of wings which have gradually 

 disappeared through disuse. 



5. Order Hemiptera, comprising the Domestic 

 and Shielded Bugs, the Plant Lice or Aphides, 

 the Scale Insects, the Cicadas, and the true Lice 

 (Anoplurd). The Hemiptera undergo what is 

 termed incomplete metamorphosis, that is to 

 say, the difference between the larva, pupa, and 

 adult insect (imago) is very slight, the pupae 

 being active creatures, and, like the larvae, more 

 or less resemble the adults in general appear- 

 ance. The Hemiptera are divided into two 

 distinctive sub-Orders ; the Hotnoptem, which 

 includes the Plant Lice or Aphides, the Cicadas, 

 the Lantern Flies, and Scale Insects, all cha- 

 racterized by having four membranous wings, 

 and the rostrum or beak attached to the frontal 

 region of the head. In the second sub-Order, 

 Heteroptera, which includes the Bugs, Water 

 Scorpions, and Pond Skaters, the basal parts of 

 the front wings are horny or leathery, while 

 the beak or rostrum springs from beneath the 

 head. Formerly considered as a separate class, 

 the true Lice or Pediculidae are now generally 

 regarded as degenerate Hemiptera, and under 

 the head Anoplura or Pediculidae, form a third 

 sub-Order. They have no wings, and are all 

 parasitic. 



6. Order Orthoptera, comprising the Cock- 

 roaches, Crickets, Grasshoppers, and Locusts. 



