108 BULLETIN 536, LT. S. DEPARTMENT OP AGRICULTURE. 



The writers believe that poisoned-bait sprays if carefully applied 

 under such commercial conditions as exist in California and Florida 

 would prove successful. Their observations indicate that honeybees 

 are in no way affected by these sprays. It is doubtful, however, if 

 poisoned-bait sprays will ever be practical under present-day cultural 

 conditions in Hawaii, where no fruit crop is grown commercially, 

 where the majority of host fruits are either inedible or not worth the 

 cost of spraying, and where sources of reinfestation from without are 

 so great. The entire subject of control by spraying with poisoned baits 

 is still open for investigation under varying conditions. 



COLD STORAGE. 



A discussion of the use to which cold-storage temperatures may be 

 put as an aid in offsetting the disastrous results of attack by the Med- 

 iterranean fruit fly was published by the writers 1 in 1916. The 

 experimental work was undertaken primarily with the hope that it 

 would be an aid in solving the discouraging problems of local horti- 

 culturists. But whatever its value in this direction, it now appears 

 that the results may be of much greater commercial importance in 

 defining the conditions under which cold-storage temperatures will 

 kill the fruit fly in stored fruits, thus rendering them free from danger 

 as transporters of this pest from one country to another, or even from 

 one infested district to another. It seems reasonable to conclude 

 that sooner or later the certification of properly refrigerated fruit will 

 be practicable. When an association of fruit growers or a community 

 awakens to a realization of the financial value of the cold-storage 

 treatment there is reason to believe it will result in the operation of 

 central refrigeration plants under the supervision of officials whose 

 guarantee will insure that all fruits sent out from the plant are abso- 

 lutely free from danger as carriers of the Mediterranean fruit fly. 



Experimental work in Australia, as an example, has shown that 

 such perishable fruits as peaches and Japanese plums can be placed on 

 the European markets in good condition if sent in cold storage, and 

 such exports have been encouraged under Government guarantees. 

 While cold storage can never lessen the damage already done by 

 larvae within fruits offered for sale or shipment, and in no way deals 

 with the root of the trouble, as a palliative, guarding fruits against 

 further attack while in storage or transit, it may become of inesti- 

 mable value. Fruits, such as apples, that contain freshly-laid eggs 

 or very young larvae may be placed upon the market, provided 

 further fruit-fly development is checked by cold storage. 



For the details of the effect of cold-storage temperatures upon the 

 eggs, larvae, and pupae of the Mediterranean fruit fly, as well as for 



'Back, E. A., and Pemberton, C E., Effect of cold-storage temperatures upon the Mediterranean 

 fruit fly. Jour. Agr. Research, v. 5, no. 15, 1916, p. 657-600; Back, E. A., and Pemberton, C. E., Effect 

 of cold-storage temperatures upon the pupae of the Mediterranean fruit fly. Jour. Agr. Research, v. 6, 

 no. 7, 1910, p. 251-260. 



