CITRUS FRUIT INSECTS IN MEDITERRANEAN COUNTRIES. 5 
yellow area. The adult flies (rig. 1, a) were commonly seen walk- 
ing about on the fruit looking for a suitable place for oviposition. By 
the last of September the fly was seen in considerable numbers where 
the fruit was beginning to ripen. In Sicily up to the last of September 
it was but rarely that a tree would be found with any of the fruit show- 
ing yellow. An occasional orange would be seen at this time almost 
entirely yellow, but these were not mature, for they were still very 
sour. Punctures were common on such fruit, as well as on some 
others almost entirely green, and as many as a dozen punctures were 
often seen in a small yellow area. Possibly the punctures were partly 
accountable for the yellowing. The flies were seen more commonly 
on the trees during the morning and evening. In the rearing cages 
during the hot weather they remained on the ground or out of the 
direct sunlight during the middle of the day. 
A large number of punctured oranges were examined during the 
last of September. Not a single one was actually found infested 
with the larvae. Ninety per cent of the punctures examined either 
contained no eggs or larvae, or contained eggs that had failed to hatch 
or larvae that were dead. The remainder contained eggs but recently 
deposited, or young larvae that had just hatched and were still within 
the egg cavity. The reason for the absence of eggs in many of the 
punctures is probably that the fly, after making the puncture, found 
conditions unsuitable for oviposition. The presence of shriveled eggs 
or dead larvae in the egg cavity must be due to the immaturity of the 
fruit. In a large majority of cases the eggs had hatched; in fact, 
only a few unhatched eggs were found. 
In immature oranges there is often a formation of gum about the 
puncture. Green oranges were known to have punctures, in some 
cases, by the presence of small globules of gum on the surface. When 
these oranges were taken from the tree and opened they were found 
to contain eggs, or larvae that had just hatched. Very soon a yellow 
spot occurs about the point of puncture, and the gum upon harden- 
ing is easily removed, and probably soon falls off naturally. A hard, 
gummy, granular tissue also forms around the egg cavity, and it is 
often possible to remove this ball of brown tissue with the egg cavity 
intact. It was at first thought that the formation of this tissue, by 
furnishing an impenetrable wall around the egg cavity or by com- 
pressing the eggs and larvae within, was the direct cause of the insect's 
mortality. But this hard tissue is not formed to any extent before 
the eggs hatch. In practically all cases where living young larvae 
were found, which indicated recent oviposition, the surrounding tissue 
was not appreciably hardened, although the brown color began to 
show. 
The egg cavity is situated in the spongy layer of the rind, just below 
the outer covering containing the oil cells. The surrounding wall of 
