349 



CHAPTER VIII. 



DESTRUCTIVE INSECTS {coiicludcd) . 



A. Hymenoptera. 



Family I. — Tenthredinidae (Sawflies). 



Description of Family. 



Sawflies have straight, usually filiform or setaceous 

 antennae, rarely club-shaped, occasionally serrate, or in S 

 doubly pectinate, and with 3 to 30 joints ; 3 ocelli ; prothorax 

 usually very short ; wings with full complement of veins, the 

 fore-wings with 1 or 2 radial and 3 or 4 cubital cells. 



Legs with a double trochanter ; the anterior tibiae with 

 two apical spines ; tarsal joints often furnished below with 

 membranous expansions, sometimes cup-shaped. 



Abdomen sessile, of 8 segments ; in 2 .with protrusible 

 serrate ovii)Ositor. 



Generation usually double, sometimes treble, but in the 

 cocoon-spinning sawflies it may be plurennial. 



Larrae usually bright-coloured, with 8 or 18 to 22 legs, 

 resenibling caterpillars but distinguishable usually by the 

 greater number of legs and by a conspicuous simple e3'e on 

 each side of the head ; they are social, and after 5 to 

 moultiiigs spin a firm cocoon which is of oval or oblong-oval 

 form and often parchment-like in consistency. 



Pupation takes place in the cocoon about 2 weeks before the 

 sawfly emerges. The pupae are soft, and encased in a barrel- 

 shaped cocoon. 



The larvae feed on needles and leaves ; they are often social 

 when young, and when disturbed assume a characteristic 

 S-like attitude. The perfect injects usually feed on honey. 

 Some species (Cimbex) girdle young beech-shoots probably in 

 order to get the sap. A few species are very destructive. 



