133 



Ichneumon Flies and their allies are parasitic Insects 

 belonging to the order Hymenoptera, and are related to 

 the Bees and Wasps. They can be recognised by the 

 presence of four transparent wings^ and by the posses- 

 sion in the female of a long needle-like ovipositor 

 or egg-laymg instrument. Almost every species of In- 

 sect IS preyed upon by some other species of Ichneumon 

 Fly or its ally. By m.eans of their ovipositor these 

 Insects pierce the skin of other Insects and lay their eggs 

 withm the body of the latter. The host Insects are not 

 killed by this operation, but continue feeding. The 

 larva^ of the parasite hatch out m due course and 

 gradually devour the blood and tissues of the host, avoid- 

 ing, however, the vital organs until the very last. The 

 parasite turns to the pup^e either within or outside the 

 host Insect, and just about the same time the latter dies. 

 Some Insects are greatly destroyed b}^ parasites and thus 

 kept in check naturally — the commxon Hawthorn Scale 

 and the Gypsy Moth are familiar examples. In America, 

 however, the Gypsy Moth has got introduced artificially, 

 and has now spread with alarming rapidity and causes 

 millions of dollars damage annually. Unfortunately the 

 natural enemies of this ^vloth were not imported, and the 

 U.S. Department of Agriculture recognise that the only 

 way of ridding the country of this Insect is by importing 

 its natural enemies or parasites from Europe. This work 

 IS now steadily going ahead on a very large scale, but 

 it IS too early to know the final result. In Italy mulberry 

 cultivation has been threatened by a Scale Insect. Diasfis 

 pejttagona. In i8gi the pest a-ssumed such serious pro- 

 portions that the Italian Government passed a legislative 

 micasure compelling m.ulberry cultivators to use all avail- 

 able means for coping with it. This, how^ever, proved of 

 little efficacy, and it was not until Professor Berlese, of 

 Florence, introduced great numbers of a minute parasite 

 from America into Italy that much headway was made. 

 From all later reports it appears that this parasite has 

 acclimatised itself to Italy and is proving of great value 

 m destroying the Mulberry Scale. 



Of all beneficial Insects the Hive Bee is the most use- 

 ful species. It is desirable here to make some reference 

 to the Isle of Wight Disease (i8), which is causing much 

 m.ortality among apiaries all over the country. The 

 epidemic is due to a minute Protozoan organism iNosenui 



