58 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
Is MEGASTIGMUS A @frect ENEMY OF THE SEED? 
It has been already stated that one feature of interest in 
connection with this Megastigmus infestation is that the insect 
is one of the Chalcididae. It has been admitted now for some 
years, practically by all entomologists, after great controversy, 
that certain Chalcids are feeders on plant-tissue, but controversy 
still exists about the genus Megastigmus. A review of the 
Chatcididae and the controversy may prove useful. 
POSITION OF THE CHALCIDIDAE IN THE INSECT WORLD. 
The well-known order of insects—the Hymenoptera, with its 
tens and tens of thousands of species, is divided into two sub- 
orders, one whose members feed on plants, ¢.g., the saw-flies and 
the wood-wasps. The other suborder, far greater in number 
of species, is known as the /efzolata, from a constriction between 
thorax and abdomen. To this suborder Petiolata belong the 
bees, ants, wasps, and ruby-wasps, and a great series known as 
the Parasitica. 
The series Parasitica—so called because of the frequency of the 
parasitic habit amongst its members—is divided up into families, of 
which the Chalcididaeis one. ‘The other well-known related families 
are the Cynzpide or Gall-flies, the Zchnewmonide or Ichneumon Flies 
proper, and the Braconide. Many of the Cynipide give rise 
to galls on plants, and their larve live in the galls caused by 
the pricking and egg-laying of the adult; others of the 
Cynipide live as guests in these galls. Some of the Cyzipide, 
however, do not feed on plant-food, but are parasitic on other 
insects. This difference of economy among members of the same 
family should be noted. 
The Jchneumonide is a very large family with larve of 
parasitic habit, most of the larve living within the body of 
their victims. The Braconide are very like the last, but are 
marked off from them structurally by differences in the wings. 
Like the Ichneumons, however, the larve of Braconide are 
parasites. 
The Chalcididae, named from the metallic lustre of their chitin 
covering, is a large family very rich in species. Some species 
reach a length of 2 inch, but the great majority are minute 
8s 
insects, some very minute. 
