ORDER HYMEXOPTERA 



211 



of a saw. This ovipositor is composed of two finely serrated 

 chitinous blades, which lie side by side, and may be pro- 

 jected from a protective sheath and moved with a saw-like 

 motion. The egg is slipped in before the saws are with- 

 drawn. After being laid, through the taking up of moisture 

 or for some other cause, the eggs swell to twice or more 



The Leaf-Mining Genera of Hymenoptera* 



* From Frost, 1925. 

 t Petiole miners. 



their original size, causing the leaf to bulge up in little 

 mounds. 



Embryonic life lasts from twelve days to two weeks and 

 at the end of that time the little larvae may be seen fully 

 formed and coiled up within the membrane of the eggs. 



