446 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



From this data, it will be seen that a constant exposure of three m.onths 

 or more at any degree from. 10° to 36° F. has proven fatal to the three 

 stages of all insects experim.ented upon; two years prior to this a some- 

 what similar experiment was conducted with a total mortality rate of 

 96.5% in the third month and 100% in the fourt.h month. It may be 

 concluded then, that dried fruit stored at any temperature from 10° to 

 36° F. will be free from, all injury by insects during the time of storage and 

 when removed at the end of the third or fourth month all stages of the 

 insects experimented upon (unless it be the egg) would be dead. The ac- 

 tion of bacteria and fungi would also apparently be suspended during 

 the time of storage. A temperature of 45° - 50° F. causes dormancy, but 

 only a low mortality. 



Such a plan for handling dried fruit would give protection during the 

 summer months, when practically all the loss occurs, so that hold-over 

 stocks for use during the summ.er or speculative m.aterial that was being 

 stored until another year could be held without risk of loss by insects. 

 Stocks remaining in storage for three or four months would be practically 

 sterile, from the insect standpoint, when removed. This is not a new 

 principle, but an application to a field where it has not bfeen commonly 

 practiced. The dealers in furs have long used cold storage as a summer 

 protection for their stocks and in 1907 Circular No 36, of the U. S. 

 Bureau of Entomology was issued by C. L. Marlott, giving temperatures 

 at which the activities of the clothes moth are checked but he speaks of 

 m.ortality only with alternating temperatures. 



The practical application of cold storage must include the comparative 

 cost of chilled and norm.al temperatures (dry storage). A com.parison of 

 the rates as established by the California railroad commission shows a 

 range in price per ton, for a season of 6 months as follows : 



Cold storage-75c. to SI. 00 per cwt. for 6 m.onths season 



Dry " (including labor) 11.1c. to 23.9c. per cwt. for 6 m.onths 

 season. 



This is an average of 70 cents per cwt. or .7 of a cwt. per pound excess 

 charge for cold storage. When the average retail price of dried fruit 

 ranges from 20 to 30 cents per pound then the seasons insurance cost is 

 from 2.3% to 3.5% of the value, and this cost will seldom be paid on any 

 of the stock sold during the winter following the production of the fruit. 

 Comparing this with the cost of insect protection during the growing 

 season, we find that pear growers estimate the cost of one spraying as 

 equivalent to 2 to 3% of the crop value with from three to six applica- 



