274 NATURAL HISTOET. 



467. The family of Sawflies is quite an extensive aber- 

 rant family. They are so called from a curious double 

 saw in the ovipositor, with which they make holes in the 

 branches and other parts of trees for the deposit of their 

 eggs. Carpenter mentions one species in England, whose 

 larvae are very destructive to turnips, devastating a whole 

 field in a few days by devouring the soft tissue of the 

 leaves ; and he states that the most eifectual remedy has 

 been found to be the introduction of ducks into the fields, 

 as they very greedily devour the larvae. 



468. Of the Aculeate division of the Hymenoptera we 

 make two subdivisions — the Predaceous, or those which 

 live on prey, and the Melliferous, or honey-collecting 

 stingers. 



469. There is one group of the Predaceous division, 

 including several families, which may be called, from their 

 peculiar habits, diggers. They are known commonly as 

 Sand and Wood Wasps. They are solitary — that is, do 

 not live in communities. They therefore are all males 

 and females, and have no neuters or workers. The fe- 

 males commonly dig out cells in the ground, or in posts 

 and timbers. In these they deposit with their eggs in- 

 sects which they have killed, so that the larvae, when 

 hatched, may have something to live upon. Sometimes 

 the insects thus deposited are only stung sufficiently to 

 render them powerless. Decomposition is thus prevent- 

 ed, and the larvse, when they come forth from the eggs, 

 kill the insects and devour them. The perfect insects 

 are active in their habits, flying about and running over 

 sand-banks with their wings in constant motion. They 

 are fond of the nectar of flowers, a very different food 

 from that which they devour in the greedy larva state. 

 Those which are sand-burrowers have strong brushes on 

 their legs with which they excavate their nests, while 

 the wood-burrowers have powerful mandibles with tooth- 

 like projections, which convert the wood into sawdust 

 in making the burrow. 



