34 BULLETIN 640, U. S, DEPARTMENT OF AGRICULTURE, 



VALUE OF ELIMINATING HOST VEGETATION. 



In Honolulu many mango and orange trees were either cut down 

 or severely trimmed, but those cut formed too small a percentage of 

 the entire host vegetation to serve a practical purpose. The only 

 places where the elimination of host vegetation yielded favorable 

 results were about banana and pineapple plantations where the work 

 was done in accordance with the regulations of the Federal Horti- 

 cultural Board. In these instances the destruction of vegetation did 

 not ehminate the adult flies, for these came in from surrounding 

 areas. It did, however, lessen the danger of immature stages becoming 

 attached to the packing material of bananas and pineapples shipped 

 to the mainland. 



Should the Mediterranean fruit fly ever become established in 

 California or the Southern States, however, where there is no such 

 wealth of native host fruits and where climatic conditions will prove 

 an important factor in control, the elimination of host vegetation 

 will play a most valuable part in remedial measures. In Algeria the 

 infestation of oranges greatly increased after such crops as peaches 

 and persimmons were grown. These fruits furnished food for the 

 fly during the summer and early fall months, which were for the fly 

 starvation months previous to the cultivation of these crops. Aided 

 by these summer crops, the fruit fly was able to increase greatly, 

 so that when the orange crop began to ripen during the fall and winter 

 months the pest could attack it with increased force. In Bermuda 

 the elimination of a comparatively few host trees, numerically speak- 

 ing, would mean the elimination of breeding places for considerable 

 areas. The destruction of unnecessary and valueless host trees will 

 not only restrict the breeding ground, but will often so break up the 

 sequence of ripening hosts that many adult flies will die while 

 attempting to bridge the starvation periods when no fruits can be 

 found for egg laving. 



DESTRUCTION OF INFESTED FRUITS AND SPRAYING. 



The destruction of infested fruits and spraying are remedial meas- 

 ures that should go hand in hand. In Honolulu they have not given 

 satisfactory results for reasons beyond the control of man, as set 

 forth on pages 24 to 33. Nevertheless, they can be made successful 

 in commercial orchards, if applied with intelligence and persistence 

 throughout a neighborhood. One indifferent neighbor can spoil the 

 work carried on in surrounding orchards. A community of growers 

 must determine in what crop their interests are centered and im- 

 partially eliminate nonessential fruits. Then, and, as a rule, not 

 until then, will labor spent on the destruction of infested fruits and 



