﻿6 



that destroy leaf-hoppers, in each country t/clong n.ostly to the 

 same groups. Egg-parasites are everywhere present Anagrus 

 of the Mymaridae attacks the eggs of the Delpliacidae ahke in 

 Europe, America, Australia, Fiji and China, and even the species 

 hardly differ in these countries ; while Paranagrns has been found 

 in Fiji, Australia and China, and Ootetrastichits of the Chalcid 

 flies in the same countries. Other Mymarids of several genera 

 attack the Jassid hoppers, some of which are also periodically 

 decimated by the excessively minute Chalcids of the family 

 Trichogrammidae, both in America and Australia. These latter 

 likewise destroy the eggs of the allied Alembracidae. Such Ful 

 gorids as lay their eggs on the surface of plants have different 

 egg-parasites. In Australia they are attacked by Proctotrupids, 

 and also by Encyrtidae of the Chalcid group, but in other coun- 

 tries their enemies have not been investigated. A foremost place 

 amongst beneficial insects must be assigned to all these egg- 

 parasites, as by destroying the egg they kill the hopper before it 

 arrives at a stage, when it can do injury. Of the other Hymenop- 

 tera, Dryinidae are no doubt ubiquitous throughout the world, 

 and they attack many species of hoppers both in the Fulgorid 

 and Jassid groups, and have also been reported as attacking 

 Membracids. Cercopidae are, so far as is known, not attacked 

 by them, but the young of these are, as is well-known to every 

 field-worker, a favorite prey of various Fossorial Hymenoptera, 

 e. g. Harpactus and Gorytcs. The Fossors likewise yield species 

 that prey on Jassids ; amongst the minute Crabronidae, for in- 

 stance, we have found the cells of the European Crossoccrus 

 gO)iager Lep. filled with a species of Typhlocyha that infests 

 beech trees. In these islands, one may see a Mimesid (Nesomi- 

 mesa hawaiicnsis) hawking for various species of Fulgorid leaf- 

 hoppers, but these are not its usual prey, which consists of certain 

 Limnobiine Diptera. It is interesting to note that its attempt 

 to seize the Fulgorids is usually a failure. As all the other 

 known Hawaiian species of Nesomifiicsa prey on the Diptera 

 mentioned, it would appear as if it were comparatively recently 

 turning its attention to the Homoptera. The singular head- 

 structure of the female wasp probably aids it in some way in 

 capturing the flies, while ineffective for holding the other prey. 

 The Dipterous Pipunculidae are also ubiquitous, and attack both 

 Jassids and Fulgorids of various groups, alike. On the whole 

 they appear to chiefly parasitize Jassids, but the Hawaiian species, 

 so far as is known, are all parasitic on Fulgorids, in fact on Del- 

 phacids only. 



