ST. HELENA 149 



through the skin and is poisoned in so doing. But in any case, 

 the use of arsenical preparations on so tender a plant as the peach, 

 and one of which the fruit-skin is so downy, would be a risky pro- 

 ceeding. 



The attacked oranges (and other fruits) soon fall to the ground, 

 and in the space of fifteen days, more or less, the larvae issue, either 

 through the original opening or through another one made for the 

 purpose, and enter the ground, where they transform to pupae, 

 remaining in this condition only a few days." (Insect Life, iii. 

 p. 80.) This condition lasts for ten days (Ormerod). Moreover, 

 the fly is active by daylight, resting at night, and does not move 

 far from the trees or bushes. There is no indication in any account 

 of any definite natural conditions which modify the liability of 

 the fruit to be attacked. Absence of insectivorous birds and bats 

 has been before suggested in the case of insular attacks, but there 

 is really no evidence to show that this is a factor. The insect 

 is destructive in South Africa, and its importance in islands may 

 really be due to the extensive part which fruit-growing plays in 

 their industrial conditions. 



I have no suggestions to make on treatment, but the following 

 methods have been suggested and employed, and agree with my 

 own independently formed ideas. 



1. REMEDIAL. In so far as no means exist for checking the 

 work of the maggot after the egg is laid, no remedial measures are 

 practical. 



2. PREVENTIVE. (a) Direct The only method which has proved 

 successful in preventing egg-laying is that of tying up the fruit or 

 fruiting trees with what is termed mosquito-netting. This can only 

 be done on a small scale. 



No insecticide is likely to be of use, except such as by its odour 

 might repel the flies ; and I cannot suggest, at present, one which 

 shall be innocuous, and at the same time possess so lasting a smell 

 as to be of practical use. The smell of any insecticides, such as 

 kerosene emulsion, is necessarily evanescent. At present, there- 

 fore, the use of an insecticide appears to be out of the question. 



(b) Indirect. Here the most suitable remedy is the collection and 

 immediate destruction of all attacked fruit, at least of all which 

 has fallen. Penzig suggests its burial in a ditch, covered with a 

 layer of quicklime ; after six months the mass is converted into a 

 valuable fertilizer. He very properly urges concerted action and 

 energetic measures on the part of the authorities, and indeed it is 

 evident that the whole value of this promising method depends on 

 the thoroughness with which it is carried out. 



The Maltese Commission (Henslow, Card. Chron., May 24, 1890) 

 also recommends the destruction of fallen fruit and the strewing 

 of the surface of the ground under the trees with one part of finely 

 powdered sulphate of lime to twenty-four parts of sand, and sub- 

 sequent watering. 



Of course, if the larvae of certain breeds do not leave the fruit 

 to pupate, the infested fruit must be picked. Miss Ormerod suggests 



