Page:The Olive Its Culture in Theory and Practice.djvu/146

120 offspring is assured. Then the fly appears; it usually lives from twenty to thirty days on the trees, passing from branch to branch and sucking the sap wherever found. It is rather torpid during the cool weather but very agile when it grows warm.

The damage caused by this fly consists in the consumption of from one-third to one-half the pulp of the berry, thus diminishing the yield of oil and in leaving inside the seed a mass of excrement, which deteriorates its quality.

There are three expedients for combating the olive fly:

FirstFirst. [sic]—To gather the fruit as soon as it is barely ripe, and crush it at once,—thus destroying the larvæ and pupæae within and preventing further multiplication. The localities most afflicted by these pests are those where the harvesting of the olive is protracted through the winter and part of the spring, either from lack of sufficient help, or to make the white oil, as is done in Lucca and on the Riviera. These, in fact, are the regions devastated most frequently by this fly. Second.—To keep the trunk of the tree clean and to spray the trees after the harvest is over with something strong enough to kill the pupae, and taking care that not even one berry remains on the ground. Third.—To cultivate the ground well about the tree, after first shaking it and thus to bury all olives containing eggs, larvae, or pupae. The fruit when picked should not be kept in heaps, or the heat engendered will cause the flies to hatch immediately. This closes the list of insects that are known to prey upon the olive. Some we already have with us, others a close degree of scrutiny may reveal, and still others let us hope we may ever be spared.

PARASITIC PLANTS OR VEGETABLE ENEMIES. The olive tree is also subject to injury from the action of several parasitical plants of which the principal and best known are the following.