INJURIOUS INSECTS. 179 



respect to the peas in the year 1810, when the produce was not much 

 more than the seed sown, and many farmers turned their swine into the 

 pea-fields, not thinking them worth harvesting. This was universal through- 

 out the kingdom." (Kirby and Spence, vol. i., p. 177.) 



Next to the locust, plant-lice are the greatest enemies of the vegetable 

 world, and, like them, are at times so numerous as to darken the air. 

 "In the year 1785, the people of the village of Selborne, in Hampshire, 

 were surprised by an abundance of Aphides, which alighted there. Persons 

 who walked the streets were covered with them, and they settled in such 

 numbers on the hedges and in the gardens, as to blacken every leaf; beds 

 of onions were quite covered with them in six days. They were observed 

 in great clouds about Farnham at the same time, and all along the vale 

 from Farnham to Alton." (G. White, p. 268, ed. 1788.) And Mr. Kirby 

 says that he once witnessed a great swarm of Aphides, when travelling late 

 in the year, in the Isle of Ely; the air was so full of them, that they 

 were constantly flying into his eyes and nostrils, and his clothes were covered 

 with them; and in 1814, they were so abundant for a few days in the 

 vicinity of Ipswich, as to be noticed by the most indifferent observers with 

 surprise. Upon this migration the pea, bean, and hop crops every year 

 entirely depend. The hop-grower is particularly at the mercy of Aphis 

 huviuli, or what he calls the fly. They are the barometer that indicates 

 the fall and the rise of his wealth. 



In the stoves and greenhouses of the gardener the Aphides often reign 

 triumphant, and if they were not discovered, and destroyed on their first 

 appearance, every plant would soon be contaminated by them, and beauty 

 be converted into deformity. Some of the genus form convenient and 

 sheltered habitations for themselves, by causing portions of the leaves of 

 peach, apricot, nectarine trees, etc., to rise into hollow red convexities; in 

 these the Aphides reside, and with their rostrum pumping out the sap, 

 in a short time occasion them to curl up, and thus deform the trees, and 

 injure the produce. And who has not observed what is commonly called 

 lioney-dew, upon the maple, beech, larch, elm, lime, willow, nut, and other 

 trees? this is the secretion of the Aphides, whose excrement has the pri- 

 vilege of emulating sugar and honey in sweetness and purity. 



"In the quality of the excrement," says Mr. Curtis, in the sixth volume 

 of the Linn. Trans., "voided by these insects, there is something very ex- 

 traordinary. Were a person accidentally to take up a book in which it 

 was gravely asserted that in some countries there were animals who voided 

 sugar in a liquid state, he would lay it down, and regard it as a fabulous 

 tale, and yet such is literally the truth. The superior size of the Aphis 

 salicis will enable the most common observer to satisfy himself on this 

 head. On looking stedfastly for a few minutes on a group of these insects, 



