108 PLANT QUARANTINE AND CONTROL ADMINISTRATION [April-June, 
holding of fruit at still lower temperatures — 28° to 32° F. for example — for the 
necessary period will destroy the early stages of this insect, conditioned, of 
course, on the fruit being able to withstand such temperatures, and even more 
important, the demonstration that in commercial practice the required degree 
of temperature can be maintained and equally distributed throughout the mass 
of stored fruit. 
The status of our present information with respect to refrigeration as a 
means of eliminating the risk of the carriage of this pest with infested fruit is 
summarized in the following paragraphs which are taken, with little change, 
from reports which have been made on this subject in answer to various in- 
quiries as to the possibility of modifying the restrictions of Quarantine 56 and 
the entry of fruits and vegetables from countries known to be invaded by the 
Mediterranean fruit fly : 
The possibility of killing fruit-fly eggs, larvae, and pupse in fruit by refrigeration was 
•discussed at considerable length in connection with the public hearing held in 1923 pre- 
liminary to the promulgation of Quarantine 56, under which restrictions were placed on 
the entry of fruits and vegetables from all foreign countries known to be generally invaded 
by the Mediterranean or other fruit flies. On account of the known general occurrence 
of the Mediterranean fruit fly in the Union of South Africa these restrictions were 
extended to that country, and as a result the authorities of that country undertook a new 
and very careful and technical examination of the subject of control by refrigeration. 
The results of this examination were communicated to this department in a formal report 
from the Acting Secretary for Agriculture. A summary of these results was later pub- 
lished by the Department of Agriculture of the Union of South Africa in the journal of 
that department for October, 1923. These experiments indicated that the fruit-fly larv» 
may live in cold storage at about 34° F. (approximately 1° C) for a period of six weeks 
and still transform to adults when removed from cold storage. This work in South 
Africa was carried out by persons who are known to this department to be highly trained 
and entirely reliable. Furthermore, it was to the interest of South Africa to demonstrate 
that refrigeration was an effective safeguard, with the intention of making the experi- 
ments the basis of an appeal for admission of shipments of restricted fruits to the United 
States. It is, therefore, worthy of note that having determined the contrary to be the 
fact the South African authorities were prompt and frank in communicating this informa- 
tion to this department. 
In confirmation of the results obtained in South Africa, and as indicating clearly the 
failure of refrigeration in a practical shipping test, reference may be made to the arrival 
at the port of New York in 1926 of a large shipment of grapes from South America which 
had been kept under refrigeration at a temperature of approximately 34° F. during the 
period of 18 days en route. These grapes on arrival proved to be generally infested with 
living fruit-fly larvse (Anastrepha) and were refused admittance. 
That commercial refrigeration of fruits and vegetables for storage or in transit is 
subject to considerable variation as to uniformity of temperature maintained, as well as 
to large opportunity for error, has been clearly demonstrated over a considerbale period 
of experimentation and examination of the subject by this department. No method has 
been devised which will maintain a uniform temperature in the different tiers, either in 
a refrigerated car or compartment. The minimum temperature in the lower tiers must 
be maintained above the freezing point, and under this limitation the upper tiers will 
average fully 4° warmer than the lowest tier, with a result of losses which it has not 
been possible to avoid from more rapid ripening or even spoiling of the upper tiers of the 
shipment. Such variation in temperatures is apt to be especially marked under refrigera- 
tion in ocean transit, and an examination of the refrigeration " log " of vessels engaged in 
fruit and vegetable carriage clearly indicates such variation. In addition to this varia- 
tion of temperature for different elevation of tiers is the variation in results, due to 
nature of packing and the arrangements for circulation of air within the refrigerating 
chambers. The variation here discussed is entirely aside from, and supplemental to, the 
important consideration of the failure so far of refrigeration to kill 100 per cent of 
fruit-fly larvae and pupse in commercial shipments. 
In view of this situation it would seem clear that refrigeration of possibly in- 
fested fruit can not for the present be considered as a reliable safeguard 
against the Mediterranean or other fruit flies, and to authorize it prior to a 
full demonstration of its complete and thoroughgoing effectiveness in ordinary 
■commercial practice might well open to menace the entire fruit industry of the 
United States. 
C. L. Marl att, 
Chief, Plant Quarantine and Control Administration. 
Mediterranean Fruit-Fly Quarantine A mended 
[Press notice] 
May 24, 1929. 
Two administrative amendments to the Mediterranean fruit-fly quarantine 
wen^ promulgated yesterday (May 23) by the Secretary of Agriculture and 
became effective immediately. 
One of these provides for movement interstate of foreign fruits and vegetables 
•entering the United States through Florida ports. The other extends the 
•time for the shipment interstate of noncitrus fruits and host vegetables from 
