SAW-FLIES. 171 



There are some bees which make their nests in 

 old walls, where they either dig for themselves a 

 hole, or oftener take advantage of a nail-hole, and so 

 save themselves much trouble. One of these bees is 

 shown on plate H, fig. 2, and is chiefly remarkable 

 for the beautifully tufted extremities of its middle 

 pair of legs. 



On plate D, fig. 7, is seen the common Hornet, 

 one of the really terrible of our insects. It mostly 

 makes its nest in hollow trees, and it behoves one to 

 keep very clear of the neighbourhood. The nest is 

 made of wood-fibre, nibbled, and made into a primi- 

 tive papier-mache. 



Two of the Saw-flies may be seen on plate J. 

 Fig. 2 is the common green Saw-fly, and fig. 3 the 

 dreaded Turnip-fly. These are called Saw-flies be- 

 cause they are furnished with saw-like implements, 

 by means of which they cut grooves in certain plants, 

 and in those grooves lay their eggs. 



Mention has already been made of the little Ich- 

 neumon fly. One of these insects is shown magni- 

 fied on plate J, fig. 12 a, and one of the large species 

 is depicted on plate H, fig. 3. The threefold appen- 

 dage to the tail is the ovipositor, or instrument by 

 means of which they pierce their victims and deposit 

 their eggs. 



There are some allied insects that pierce vegetables 

 instead of insects ; and one of their works may be 

 seen figured on plate A, where a bramble-branch has 



