142 - BOARD OF AGRICULTURE. 



of aphis, a Greek word, meaning an exhauster or depriver of 

 strength, belonging to the genus Pemphigus , of Hartig, the 

 Eriosoma or woolly-bodied aphides, mentioned by Dr. Harris. 

 These are busily engaged in sucking the sap, and if they have 

 been at work for more than one season, there will frequently be 

 excrescences of solid wood, varying from the size of a mustard 

 seed to two or three inches in diameters, growing from the 

 roots of the tree like bunches of small potatoes ; these are 

 caused by the punctures of the plant-lice, in the same way as the 

 galls upon the oak, and swellings of the stem of the golden-rod 

 by other species of insects. Among these tubers, and clustered 

 around the roots, are the young, or larvce, of a light color, and 

 about one-twenty-fifth of an inch in length, having a small 

 thread, of a whitish substance, extending from the tip of the 

 abdomen. At the close of the season, the adult insects of about 

 one-fourth of an inch in length, and furnished with wings, will 

 be found. These are of a black color, but almost covered with 

 a bluish-white down, upon the upper surface, resembling fine 

 wool ; their wings are transparent, and folded over the body like 

 a roof. Their fecundity is a marvellous theme, and is a part of 

 the history of the race of plant-lice. According to Reaumur, 

 one aphis may become, in a single season, the progenitor of over 

 five thousand millions of descendants. The egg deposited in 

 the fall is hatched in the spring, each one producing a female ; 

 she in the course of a few hours becomes a mother and gives 

 birth, not to an egg, but to a living daughter, who in turn, may 

 be in a week from the commencement of her existence, a great- 

 grandmother. This continual propagation of females continues 

 through the summer, when the males again occur among the 

 births, and both sexes then acquiring wings, copulate and 

 deposit eggs for the spring brood. 



With such enormous powers of multiplication, we might 

 reasonably apprehend the speedy destruction of all our crops 

 by this little creature, were it not that their insect enemies and 

 other causes tend to reduce their numbers materially, and keep 

 in check this vast army of suckei^, or exhausters, as they are 

 significantly named. The little black-spotted red beetle, which 

 children call the lady-bird, the lace-winged fly, or golden-eye, 

 and the black and yellow-striped flies of the Syrphus tribe, as 

 well as internal Ilymenopterous parasites, are continually feed- 



