December, ’18] 
RUST: ANASTREPHA FRATERCULUS 
459 
this period the condition has become more and more wide-spread and 
the percentage of infested oranges has increased until during the 
autumn of the present year (March-April and May, 1918) a loss was 
experienced of nearly 50 per cent, of the oranges in some sections; and 
one grower reports the dropping of at least three-fourths of his crop of 
pomelos through the agency of this insect. 
Conditions at present are worst in the Province of Tucuman, and it 
is in the central and southern portions of this province only that 
oranges are severely damaged. On the other hand, almost all thin- 
skinned fruits are more or less subject to infestation in most parts of 
Northern Argentina. In the Province of Salta and the majority of the 
Province of Jujuy peaches and apricots are generally almost a total 
loss, due to the rot engendered by these maggots, and chirimoyas or 
“ custard apples,” plums, etc., are regarded with suspicion until after 
a thorough examination. Although very excellent oranges have been 
produced in that section (notably at Oran, Salta) for more than one 
hundred years, the fruit-fly does not seem to have adapted itself to 
that host to any great extent, as yet, in the two provinces named, but 
indications point to a heavier infestation in the future. The writer 
saw evidences of oviposition in nearly every orchard visited in those 
provinces during May of the present year, and ventures that before 
the lapse of many years even the wild oranges in the forests around 
Oran will be the regular hosts of this fruit-fly, which seems to be grad¬ 
ually extending its ravages to fruits heretofore considered immune. 
Conditions which will bring about a serious infestation of these oranges 
will be a season when many flies have emerged, followed by a sudden 
diminishing in the usual quantity of thin-skinned fruits of late summer 
or autumn, which will force large numbers of flies to oviposit in the 
oranges. 
Description of the Fly 
The adult of the maggot which makes all this havoc might be said 
to resemble, in a general way, the common house-fly, except that the 
former is yellowish-brown in color and of somewhat larger size. In 
this matter of size, some latitude should be allowed, for individuals of 
both sexes vary greatly in this particular, in accordance with the con¬ 
ditions under which they developed. The writer has seen a statement 
to the effect that the female measured about 12 mm. in length (exclu¬ 
sive of the ovipositor) by slightly more than 25 mm. across the ex¬ 
tended wings. The foregoing is, however, a trifle large, as an average, 
for the flies which occur in the region under discussion. Data obtained 
from the examination of large series of individuals show the following 
characters: 
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