BENEFICIAL INSECTS. 401 



colours. Over 4000 species have already been described, and they 

 occur in all parts of the world. The eggs are laid in galls, or in 

 nests of the higher Hymenoptera, so that the larva may feed on the 

 contained maggot. Some species attack the caterpillars of moths, and 

 others, like Chains ovata, feed in pupae. 



" Proctotrypidae. The Proctotrypidce are a large family of small 

 Hymenoptera, distinguished from the Ghalcididce by the pronotum 

 being closely fused with the mesothorax, and reaching back to the 

 bases of the fore-wings. The neuration varies greatly : in some genera 

 a few nervurgs and cells are present ; in others, none. The hind-body 

 is pointed at the tip, and the ovipositor is tubular. The trochanters 

 are usually segmented, but in some genera they are simple. The 

 larvae live parasitically within the bodies of insects ; those of some 

 very minute species find food enough in other insects' eggs. In some 

 Proctotrypidce the larva in its first stage is broad in front, and tapers 

 behind to a point whence spring several tail-processes ; this is ulti- 

 mately changed into the ordinary Hymenopterous maggot. Some 

 genera of the sub-family Mijmarlme, tiny and delicate insects with 

 narrow wings fringed with long hairs, are aquatic in their habits, and 

 their larvae are believed to feed in the eggs of dragon-flies. The 

 Pwdotrypiche have a world-wide range, and must number many 

 thousands of species." 



The above remarks are given simply with the idea of suggesting 

 the field of study for the student. As a general rule, the student 

 will find sufficient scope, along with other subjects, in confining him- 

 self entirely to the injurious species. If, however, he can possibly 

 study "beneficial insects" as here indicated, he will find the best 

 method of doing so to simply collect the various species in the 

 hatching-boxes. In the case of some insects this is specially interest- 

 ing, as for example in the "oak-apple" gall, from which various 

 parasites hatch out nearly all the year round. Again, it may be 

 said that it is essential to know something of parasites, as, to a 

 beginner, they may often in the hatching-box be mistaken for the 

 real injurious species. It is also of considerable importance to study 

 parasites, as in certain cases they may change their habits, as, for 

 example, in Megastigmus, which has been long known as a parasite on 

 "oak galls," and recently has been discovered as a deadly enemy to 

 the seeds of Douglas fir. 



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