228 ANNUAL EEPOKTS OP DEPAETMENT OF AGEICULTURE. 



beetles, were also found in Argentine shipments. Upwards of 20 

 cargoes and many elevators were examined at the ports of Baltimore, 

 New York, Brooklyn, and New Jersey. In many cases the grain had 

 been held too long and was in unfit condition for seed or for human 

 food. 



A new pest, which attracted attention from its mjuries to cacao in 

 store, and to its products, such as cocoa and chocolate, was studied 

 and an account of it will be available for publication shortly. Another 

 insect which had previously been considered a scavenger was found to 

 be very destructive in Aiississippi and neighbormg States to corn 

 which has been left long in the field and taken in store, and a special 

 investigation was started. 



Fumigation with various chemicals, including three that are com- 

 pai-atively new for this purpose, was continued. One of these, para- 

 dichlorobenzene, was the subject of a special investigation. 



What appears to be a new household pest in this comitry, although 

 indications are that it'may have been introduced 5 years earlier, was 

 found in the District of Columbia, where it was quite destructive to 

 upholstering, attacking especially the packing, which is chiefly of 

 imported hogs' bristles. A building in which it was most abundant 

 was successfully fumigated with hydrocyanic-acid gas. 



The use of naphthalene balls as a means of preventing weevils from 

 infesting stored corn, cowpeas, and other products was investigated, 

 and the effect of heat and cold for the preservation of stored products 

 was given special attention. 



Work was conducted in California in the control of fruit insects by 

 means of sealed paper cartons. The insects particularly concerned 

 are the Indian-meal moth, the fig moth, the dried-fruit beetle, the 

 saw-toothed grain beetle, and others. Several cartons were devised, 

 as well as the proper methods of sealing each. The secret of preparing 

 an insect-free package of dried fruit was shown to be sterilization at 

 a temperatm-e of 180° F. and protection from future mfestation by 

 the use of an insect-proof packing room and sealing in sterile cartons 

 or packages. 



INVESTIGATIONS OF INSECTS AFFECTING TROPICAL AND SUBTROPICAL 



FRUITS. 



Mr. C. L. Marlatt contmued in immediate charge of the bureau's 

 investigations of tropical and subtropical fruit insects. 



Improvement in methods of fumigation. — ^An important advance 

 was made in fumigation methods. While the usual methods of 

 destroying insects by fumigating with carbon bisulphid or hydro- 

 cyanic-acid gas have been found to be very effective in controlhng 

 certain insect pests, a reliable method of destroying insects Ukely 

 to be present in plants and plant products imported from foreign 

 countries has long been needed. This is especially true from the 

 fact that the exclusion of insects at the port of export by any form 

 of inspection is frequently impracticable. 



In order to increase the diffusion of hydrocyanic-acid gas a fumi- 

 gation chamber was constructed which would afford a partial vacuum, 

 m the belief that a much larger amount of gas might thus be forced 

 into the crevices of the material to be fumig^ated than would be 

 possible if the gas were dependent upon diffusion under normal 



