ANTS, BEES, WASPS, AND THEIR KINDRED 109 



and in the large pine forests of Germany and Northern 

 Europe these insects have proved serious pests. 



The insects to which the name " saw-fly " is most 

 commonly applied belong to the family Tenthrcdinida, 

 of which we have numerous indigenous species. One 

 of the largest is Trichiosoma tibialis, whose caterpillar 

 feeds on hawthorn, and ultimately spins a hard, brown 

 cocoon on a twig. The perfect insect appears in early 

 spring, and is not unlike a large bee, but may readily be 

 distinguished by its long, clubbed antennae. Another 

 member of this family is the gooseberry saw-fly, 1 

 which, as a larva, ravages our gooseberry bushes. In 

 some instances the larvae of saw-flies feed in galls. 

 For instance, the crimson horse-bean galls that are often 

 so numerous on the leaves of the crack willow are caused 

 by a species known as Nematus gallicola. 



In the second sub-order 2 of the Hymenoptera the 

 abdomen is constricted behind the first segment to 

 form a " waist." The ovipositor may be merely a tool 

 for inserting the eggs, but in the higher families it is 

 often modified to act as a sting, the eggs then passing, 

 not through the organ itself, but through an aperture 

 at its base. The larva is always a legless grub, whose 

 welfare depends upon the instinctive preparations of 

 the parent, or (where social species are concerned) 

 upon the daily ministrations of the " workers " of the 

 community. This sub-order comprises by far the 

 larger number of the Hymenoptera. Many families 

 are recognized, among them being the following : 



The gall-wasps 3 are so called because many of the 



species are concerned in the production of galls, in 



which the grubs feed. These galls are found on 



several kinds of plants, but most commonly on the oak. 



1 Nematus ribesii. 2 Apocrita. 3 Cynipida. 



