THE MEDITERRANEAN FRUIT-FLY. 19 



The only explanation seems to be that the bait, being evenly distributed over 

 the trees, priclily pears, bush, etc., around the orchard, was so easily available 

 that practically all of the flies present during any one day found it very quickly, 

 and fed on it to their destruction. It should be stated here that, even though 

 the flies do not "drop dead" immediately after feeding on the bait, the poison 

 begins to take effect in a very short time, and completes their destruction in 

 about 24 hours. But during this time the flies, as indicated by specimens kept 

 under observation in cages, are too sick to think of depositing eggs. The same 

 fate evidently awaited the fresh flies as they emerged from the ground. The 

 fact that they must feed for a number of days before the eggs are sufficiently 

 mature to be deposited gives ample time for them to find the bait. 



If any of the flies that emerged from the mass of infested fruit under the 

 control trees found their way to the treated orchard they must have found the 

 bait at once on arrival and died without depositing eggs. This shows that 

 either the flies ordinarily do not travel over a space of 400 yards or else they 

 find the bait so quickly that there is uothiug to fear from them. This also has 

 an important bearing on the question of contamination coming from neglected 

 orchards, for it indicates that the progressive fruit grower will i-eap the full 

 benefit of his care in treating his trees, even though his neighbor's orchard, or 

 the native bush near by, is full of flies. 



In these tests in 1909 the formiihi used was sugar 3 pounds, arsenate 

 of lead 4 ounces, water 5 gallons. Rains interfere much with the 

 use of the spray and applications must be repeated to maintain it 

 on the trees. A total of 14 applications was made from January 15 

 to March 20, the expense for material being about 8 cents per tree. 

 The poisoned-bait method of controlling this and other fruit-flies 

 would appear entirely feasible, especialh^ in more or less arid regions, 

 where the spray would not be washed off by rains. On the other 

 hand, the application of the spray to fruit just as it is approaching 

 maturity might prove objectionable. The poisoned-bait method is 

 already being tested in the United States for the control of the apple 

 maggot. The results of this work, so far as the writer is aware, have 

 not been indicated. 



Considerable interest was aroused in the so-called paraffin remedy, 

 first developed in AYest Australia, which consists in trapping the 

 adidt flies with kero.sene oil. The oil is said to be particularly at- 

 tractive to flies, and the vessels containing kerosene are placed in the 

 forks of the tree and attract them to their death in considerable num- 

 bers. It has been found, however, that a large proportion of the 

 insects thus trapped are males, and practical tests of the method by 

 Lounsbury showed that little, if any, protection to the fruit resulted. 



