464 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
erally too green and very few if any of the first maggots develop, even 
if the eggs hatch. But from the middle of March to the last of April, 
or even longer during' favorable weather, larvae regularly develop in 
many of the oranges of this section. Especially is this true in thin- 
skinned varieties or those with a loose peel such as the tangerines have. 
Eggs are often deposited in large numbers in oranges, but no larvae 
develop. This was very puzzling at first but it has since been found 
that during oviposition some of the oil cells, so numerous in citrus 
fruits, are often ruptured and the strong essential oil thus liberated 
destroys the eggs. But even if this accident is escaped, not all danger 
is passed, for if the eggs be deposited in very thick-skinned fruits such 
as bitter oranges, pomelos, or even some seedling oranges, the larvae 
are very apt to starve to death before they can penetrate the innutri- 
tious rind and arrive at the pulp on which alone they can thrive. 
Another puzzling question was why the fruit so often dropped when 
no signs of larvae could be found in them. After extensive experiments 
it was proven to the writer’s satisfaction that even if no eggs were 
deposited by the female at the time oviposition was attempted, yet the 
resulting punctures were often sufficient to allow the fruits to become 
infested with Colletotrichum and other fungus spores or by bacterial 
rots which caused a premature ripening and fall of the fruit, and it is 
probable that the ovipositor of the female really acts as the vehicle of 
infection in many cases. Especially was it noted that pomelos are 
almost sure to develop typical Colletotrichum spots after being “stung” 
by the fly, and it is due to the fungus and not to the fly larvae that they 
drop prematurely, for the fly larvae rarely reach maturity by tunneling 
the thick rind of this fruit. The eggs may hatch and the young mag¬ 
gots may feed for awhile but they generally die before pupating. 
The growth of A. fraterculus larvae in citrus fruits is slower than in 
the other fruits mentioned, and this may be due partly to the qualities 
of the fruits themselves, but is more apt to be the effect of the lower 
temperature which always occurs during the autumn and winter, when 
the citrus fruits are ripening. During the first part of the season larvae 
developed in the orange in from twenty to thirty days and then remain 
in the pupal stage from fifteen to twenty-five days longer (according 
to temperature) or a matter of from thirty-five to fifty-five days for 
the immature stages, but as the weather grows colder development 
becomes slower until finally it stops completely and the coldest season 
is spent in a quiescent state by both larvae and pupae, but the adult 
continues actively feeding during warm days even if the temperature 
has dropped as low as freezing the previous night. Thus we have A. 
fraterculus passing the coldest months of July and August as larvae in 
citrus fruits, as pupae protected by the soil, and as adults, which have 
