350 



UTILITARIAN ZOOLOGY 



Fleas (Dipt era], but forms extremely injurious to cultivated and 

 other plants are to be found in several orders, as a brief summary 

 will show. It will be convenient to mention at the same time 

 some of the species which damage food, clothing, buildings, 

 &c. &c. 



Bugs (Hemipterd}. By means of their piercing and suctorial 

 mouth-parts innumerable members of this order are able to 

 feed upon the sap of plants, often with the most deplorable 

 consequences. Aphides or Green- Flies (Aphidce] and Scale- 

 Insects or Mealy Bugs (Coccida) are among the most mis- 

 chievous, for though of small 

 size they are astoundingly pro- 



-d 



Fig. 1246. Vine Aphis (Phylloxera vaslatrix) 



a, Wingless root-sucking female; b, winged over- 

 ground female; c, wingless overground female; d t 

 male; e, gall-producing female. 



Fig. 1247. Apple Scale- Insect (My- 

 tilaspis pomorum], enlarged. A, Male. 

 B, Female, c, Nymph. 



lific. Aphides are often popularly known as " blight", and nearly 

 200 species of them are British, while some 800 have altogether 

 been described. Many important cultivated plants are infested 

 by particular kinds of Aphis, as will be gathered from the names 

 of the following : Corn Aphis (Aphis cerealis\ Oat Aphis (A. 

 avence). Bean Aphis (A. fabcz). Cabbage Aphis (A. brassic(z\ 

 Turnip Aphis (A. rapce\ Hop Aphis (A. humuli\ Cherry Aphis 

 (A. cerasi\ Plum Aphis (A. pruni}, &c. &c. Enormous damage 

 is done in vineyards by the Vine Aphis (Phylloxera devastatrix, 

 fig. 1 246). During the spring and summer wingless females work 

 havoc upon the roots, which swell up into small galls. They lay 

 unfertilized eggs, which hatch out into forms like themselves, and 

 there may be as many as eight generations of the kind produced 

 during the season. But the last batch of these eggs produced in 

 autumn gives rise to wingless males and winged females, that live- 

 above-ground and attack the leaves. The fertilized "winter- 



