EXTENT OF GIPSY-MOTH PARASITISM ABROAD. 
129 
accomplished fact, although of course there is no assurance that it is 
continuous and perfect. 
The final outcome of the Russian experience was, therefore, the 
opposite of what might have been expected, and it resulted in a firmer 
determination than ever to carry the work through to its end. 
EfeRASITISM OF THE GD?SI MOTH IN SOUTHERN FRANCE. 
Following the 10 days in Russia a shorter period was spent by the 
junior author in somewhat similar field work in southern France, 
where, with the aid of M. Dillon, he was enabled to visit the localities 
from which the largest, and in that respect the most satisfactory, 
shipments of parasite material ever received at the laboratory were 
collected. As the direct result of the senior author's visit to Europe 
in 1009 some thousands of boxes containing hundreds of thousands of 
gipsy-moth caterpillars had been collected in the vicinity of llyeres, 
about 50 miles to the eastward of Marseilles. These caterpillars were 
largely living upon receipt, and in the winter of 1909-10 Mr. W. B. 
Thompson dissected several hundred preserved specimens and the 
actual percent age of parasit ism was t bus (let erinined. Some few pupa3 
which had also been received from the same locality made possible a 
fair undersl anding of the extent to which the pups ^ ere parasitized. 
The results of these investigations, taken in connection with the 
actual rearing work, were disappointing. It was evident that the 
moth was fairly common in t he legion from which the material was 
collected — as common, perhaps, as it would need to be in Massachu- 
setts to provide for an increase of sixfold annually. Nevertheless, 
the amount of parasitism which was indicated by this, the most 
thorough study of parasitism of the gipsy moth abroad which was 
ever undertaken in the laboratory, was less than enough to offset a 
twofold, much less a sixfold, increase. 
For this reason much curiosity was felt as to the conditions wJiich 
prevailed in a country where parasitism of such comparatively insig- 
nificant proportions w as sufficient. 
Nose oner was the character of the country districts in this portion 
of France seen than the wonder which had been felt at the small per- 
centage of parasitism which w its sufficient to hold it in check w as 
replaced by a much greater astonishment that the gipsy moth should 
exist under such conditions at all. It w as a country of olive orchards 
and vineyards, with a strip along the littoral which was so nearly 
frostless as to permit the culture of citrus fruits, and even of date 
palms. The hills were semiarid, with the soil exceedingly scanty and 
often covered by loose stones. The principal forests consisted largely 
of cork oak and pine, except in the low and w ell-w atered valleys and 
bottom lands where other trees in considerable variety occurred. 
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