CITRUS FEUIT INSECTS IN" MEDITERRANEAN COUNTRIES. 5 



yellow area. The adult dies (fig. 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 larva?. Ninety per cent of the punctures examined either 

 contained no eggs or larvse, or contained eggs that had failed to hatch 

 or larvse that were dead. The remainder contained eggs but recently 

 deposited, or young larvse 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 larvse 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 larvse 

 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 



