186 HYMENOPTEKA (SAWFLIES). 



The Sawflies and Wood-wasps (Hymenoptera 

 sessiliventres). 



Sawflies and Wood-wasps are phytophagous, with sessile ab- 

 domen, the larvse resembling caterpillars in the former group. 



(1) The Sawflies or Ti^'iithrerlinidai have a sessile abdomen, 

 with short saw-like borer (fig.^89) of a complex structure, which 

 is only exerted during egg -laying. The mandibles are well 

 formed, but the rest of the mouth is weak. The sawflies lay 

 their eggs by cutting a slit in the epidermis of the leaf ; in 



Fic. 89.— Saw of a Female Sawfly (irreatly enlarj,^ed). 



this a single ovum is deposited, and the slit may be closed by 

 a gummy excretion. The larvse are called " False-caterpillai-s," 

 and feed voraciously on leaves and even fruit. Some form 

 galls on willows, &c. They have twenty-two or more legs, and 

 can thns be told from the Lepidopterous larva. Often when 

 young the larvte are gregarious, but separate as they gro^v older. 

 They all, or nearly all, spin cocoons, wliich may generally be 

 found in the ground beneath where the larvaj have been 

 feeding. The cocoons are often co\evcd externally with small 

 particles of earth. They remain in this position all the winter 



