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-laying instrument. Almost every species of In- 
sect 1s preyed upon by some other species of Ichneumon 
Fly or its ally. By means of their ovipositor these 
Insects pierce the skin of other Insects and lay their eggs 
within the body of the latter. The host Insects are not 
killed by this operation, but continue feeding. The 
larvee of the parasite hatch out in 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 pupz either within or outside. the 
host Insect, and just about the same time the latter dies. 
Some Insects are greatly destroyed by parasites and thus 
kept in check naturally—the common 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 Moth 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. Dzasgzs 
pentagona. In 1891 the pest assumed such serious pro- 
portions that the italian Government passed a legislative 
measure compelling mulberry cultivators to use all avail- 
able means for coping with it. This, however, 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 
in 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 (18), which is causing much 
mortality among apiaries all over the country. The 
epidemic is due to a minute Protozoan organism (Nosema 
