Sa w-flies and wood- wasps. 



575 



TenthredinidcE, but ig most frequently nine, especially in the more typical 



sub-families, in which the joints are long, cylindrical, and 



well-marked. In one sub-family, however, the short, thick Antennsa of Saw 



antennae are composed of only three well-separated joints ; Flies. 



the scape, a short joint, and a long terminal one composed of 



several fused together. Sometimes this third joint is bifid, each antenna 



being thus double nearly to the base. 



Our fruit-trees often suffer severely from the attacks of the larvfe of various 

 saw-flies. Those best known to ordinary observers are probably the small 

 greenish or yellowish black-dotted larvre which frequently 

 strip our gooseberry and currant bushes of all their leaves, Saw-Flies 

 and which develop into small black and yellow four-winged injurious to 

 flies about half-an-inch in expanse, belonging to various species ^'''^i* trees, 

 of thegreat genus Nematu (Panzer. ). But these bushes are li- 

 able to the attacks of the larvfe of saw-flies belonging to other sub-families than 

 iheNematince., and also by the larvse of various Lepidoptera and other insects. 

 The Siricidce, or wood- wasps, burrow in the larva state in timber, with which 

 they are frequently imported into this country. The commonest and most 



conspicuous species is 

 Sirex gigas (Linn.),avery Wood-Wasps 

 formidable - looking in- (Siricidct). 

 sect, the large females of 

 which sometimes measure nearly two 

 inches across the wings, though many, 

 specimens are much smaller ; for wood- 

 feeding insects, as a rule, vary very 

 much, both in size, and in the length of 

 time which they require to reach matu- 

 rity. It is black and yellow, and the 

 Fig. 53.-Sirex gigas. M.le. Nat. si.e. female has a stout ovipositor projecting 



behmd the body for about one-third of 

 its length. The abdomen of the male, on the other hand, terminates in a 

 rectangle. Tliese insects 

 will soraetimesemergefrom 

 planks of deal or pine, 

 which have been built into 

 the floors or fittings of a 

 house, and make a loud 

 buzzing, which has some- 

 times led to their beingmis- 

 taken for hornets, but they 

 are really quite harmless. 



The Oallicolce, or gall- 

 flies, are far better known 

 by the galls which grow 

 upon the leaf or stalk in 

 which they have deposited 

 their oggs than by the flies 

 themselves, which are gen- 

 erally small shining black 

 or reddish insects, with 

 long antennfe and trans- 

 parent wings, with the very 



Fig. H.— Sirex gigas. Female, Nat, size. 



