160 BOARD OF AGRICULTURE. 



holes under bark, or in crevices, &c., and for this purpose they 

 are often two or three times the length of the body. There are 

 scarcely any insects which do not suffer from the attacks of these 

 parasites. They are the best friends of ag-ricultnrists. Tiie eggs 

 are either laid on the surface of the larva?, when they eat their 

 way inwards ; or the egg being placed within the body of the 

 victim, it hatches out and feeds on the fatty issues of the larvas, 

 gradually consuming its life until the parasite turns to pupa, when 

 it dies. There may be one large Ichneumon thus feeding within, 

 or numbers of them. Thus the caterpillar of Acronycfa, found on 

 the alder in October, is often seen adhering to the leaf, preserving 

 the semblance of life, while the inside of the body is packed with 

 little cocoons placed vertically next to one another. 



Of course Ichneumons abound most in. summer when larvaj are 

 most plenty, when they are found in great numbers on umbellifer- 

 ous flowers. But many species appear in April. Tlie species of 

 Ophion, with compressed ai^hed yellow bodies, come to light in 

 summer. In Europe nearly 2000 species of this family have been 

 described. Evam'a, with its very short abdomen, Pelednus, with 

 a very long one, which is abundant in summer, represent a small 

 family, the Evaniidoe, which lead to the 



Gynipidce, or Gall-flies. The species are of small size, with 

 short broad heads, a globular thorax, and short compressed abdo- 

 men. With their long slender ovipositor they insert their eggs into 

 leaves, &c. which causes b}'- the irritation a hollow swelling on the 

 leaves, buds or stalks of plants. Those large swellings on oaks 

 imported from the East, known as galls, have given the name tt) these 

 productions. Galls are of various forms and sizes, and diflfer with 

 the species of gall-fly that produces them. They ' Fia. 8. 

 may contain one or several grubs, which are 

 small, fleshy and footless, with tubercles in the 

 lower surface instead of feet, to move by. The 

 eggs increase in size as the gall itself enlarges. 

 A wingless species in England makes its galls at 

 the foot of the oak, beach, &c. Cynip dichlocerus, 

 (Fig. 8,) forms long galls in the stem of rose bushes. 



Uroceridce, Boring-sawflies. These rather rare insects pass their 

 lives as borers in the trunks of trees. Unlike the previous families 

 of hymenopters, their larvae are long, cylindrical, and furnished 

 with three pairs of true legs. The saw-flies are likewise cj'l'ndri- 

 cal and long, and the sides of the body continuous, not being 



