222 ECONOMIC ENTOMOLOGY. 



each of the great insect families contributes its quota to the 

 devastating army. Certain families — notably, the Beetles (Coleop- 

 tera), the Bees, Wasps, Ants, etc. (Hymenoptera), the Ephemeras, 

 Dragon-Flies, etc. (Neuroptera) — send us friends as well as foes ; 

 others — like the Aphides (Homoptera) are unmixed evils. 

 The Aphides are, perhaps, the most terrible and dangerous 

 of all our scourges, and one of the most difficult to overcome, 

 their amazing power of increase being unequalled throughout the 

 animal kingdom. There is scarcely a plant that is not attacked 

 by them, nor a locality where they are not to be found in numbers, 

 and, under their popular name of " blight," dreaded by all gar- 

 deners and cultivators. At first sight it would hardly seem that they 

 could be worthy of much attention. Their round, short bodies, 

 nearly all belly, are carried on the frailest of legs ; their habits are 

 so sedentary that they seem intended to remain stationary ; where 

 they are born, for the most part, there they live and die, without 

 giving any evidence of the instinct so frequently met with in 

 insects. Their lives might almost be described as vegetable. 

 Yet their organisation is most singular, and their fecundity in 

 certain seasons so prodigious as to make them a real scourge. 

 They infest every kind of tree, plant, or flower. The rarest 

 flowers in our hot-houses and the commonest flowers of the 

 hedgerows alike serve them for home and food ; in short, they are of 

 all climates and all seasons. 



They are both oviparous and viviparous. Their eggs, fixed to 

 the plants by a viscid secretion, have the appearance of little, 

 black, oval, shiny grains, deposited irregularly in large numbers on 

 the sheltered side of branch or leaf. The young larva when extruded 

 from the egg is nearly of its full size, and presents but little differ- 

 ence in appearance to the perfect insect. It emerges from the 

 egg by a sort of trap or cover, and falls out backwards. Shortly 

 after their birth, the young aphides work tlieir way on to the tender- 

 est and greenest part of the plant on which they find themselves. 

 They crowd close together, their heads usually pointing to a 

 common centre, and fix themselves by means of the large beak 

 with which their mouth is furnished, and through which they 

 incessantly suck up the sap of the plant, exhausting it and causing 

 strange excrescences like galls, and in the end the plant becomes 



