SCIENCE AND INDUSTRY. 
acclimatised they were liberated when and where desired. From 1905 
to 1918 more than thirty species of parasites were imported from 
Europe and Japan. The problem of the control of these two moths 
has not been an easy one to solve. From a study of this life-history of 
the Gipsy moth it was ascertained that the probable potential increase 
is about 250 fold annually. On account of very heavy death rates, the 
effective rate of increase is only six to ten fold. ‘How, then, could 
sufficient parasites be secured to keep the development in check? If 
the increase annually be six fold, then five out of every six insects (over 
80 per cent.) in any condition would require to be effectively parasitized, 
and if ten fold, then nine out of every ten must be similarly destroyed. 
To effect these results it therefore became necessary to secure a sequence 
of parasites, attacking every stage of development—the egg, caterpillar, 
pupa, and moth itself. This required considerable research work, and 
these investigations have been responsible for some of the most noted 
advancements in biological control work. The most successful parasites 
(Lockhead, Ec. Ent.) now include the following :— 
Gipsy Moth.—Egg parasites 
Larya parasites 
Pupa parasites 
Brown-tail Moth.—Egg parasites 
Larva parasites 
imported Ichneumons. 
imported Tachinids. 
imported Predatory Beetle. 
imported Chalcid. 
Native Chaleid. 
imported Chalcid. 
imported Braconids. 
imported 'Tachinids. 
imported Beetle. 
native Chalcid. 
imported Chalcid. 
native Ichneumon. 
Pupa parasites 
me eee eee il 
8. At the time when the Gipsy Moth parasites were being imported 
the parasites of the Cotton Boll Worm were also under extensive propa- 
gations. The Cotton Boll Worm is the larva of a moth Leliothis 
obsoleta Fab. belonging to the family Noctuidae, i.c., night fliers. Until 
the advent of the Mexican cotton boll weeyil (Anthonomus grandis Bob.) 
the Boll Wiorm was by far the most serious of the numerous insect 
pests of the cotton plant. The coming of the: weevil has not lessened 
the destructiveness of the Boll Worm, but its injuries have been over- 
shadowed by the more serious depredations of the weevil. This weevil 
first attracted attention in Texas in 1894, and it has the record of 
developing in less than twenty years from a most obscure species to one 
of the most important economically in the world. The moth eliothis 
was known about 100 years before the weevil, and is practically cosmo- 
politan. Its original home was most likely America. In Australia it 
is better known as the Maize Moth, and in other countries it is called 
the Tomato Moth, and in many parts of the United States of America, — 
in the larval stage, as the Corn Ear Worm. In 1900 it caused a loss 
of sweet corn of approximately £400,000, and an annual loss of over 
. £3,000,000, or on corn, cotton, and tomatoes of over £5,000,000 annually. 
Tn 1903 the weevil caused a loss of £3,000,000; in 1904, of £4,500,000; 
and in 1909, of £18,000,000. From 1895 to 1914 the loss caused by 
the weevil has been estimated (by the United States of America Bureau 
of Entomology) at £140,000,000. We already have the Boll Worm Moth; 
can we prevent the entrance of the weevil (Anthonomus)? In many 
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