BUREAU OF ENTOMOLOGY. 233 



products, such as cocoa and chocolate, and more recently during the 

 past year has been found to be noticeably injurious to rice in store. 

 It also affects dried fruits and other stored products. Special 

 studies of this insect have been made. 



The Angoumois grain moth has been studied in relation to its 

 reinfestation of storehouses and cribs from the field. The different 

 species of grain beetles have been under continuous observation, and 

 some new data have been gathered in regard to the life economy of 

 the meal worms. The larder beetle has been studied, and consider- 

 able attention has been given to some of the minor insect enemies of 

 stored products which have been introduced into this country recently 

 and are being disseminated by commerce. 



The mites which affect flour, dried fruits, and other stored products 

 have been studied with a view to a report on the topic. 



Work has been begun with a view to determine whether or not the 

 process of sulphuring to which dried fruits are subjected acts as a 

 more or less permanent protection against insect ravages. Thus far 

 the results have been negative. 



New machinery has been installed for determining the effect of 

 heat on insects infesting stored products of all kinds. Preliminary 

 tests have been made. 



INSECTS AFFECTING TROPICAL AND SUBTROPICAL FRUITS. 



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

 investigations of tropical and subtropical fruit insects. 



Improved method of fumigation. — As indicated in the last an- 

 nual report, an important advance has been made in fumigation 

 methods. During the year experiments have been conducted with the 

 object of determining the practicability of fumigating dormant and 

 growing plants and various kinds of seeds in a partial vacuum. 

 Definite data have been secured on this method of disinfection, in- 

 cluding the effect of the gas on plants and seeds, and the ultimate 

 effect of such treatment on the vitality of the material fumigated. 



Citrus-fruit insects in California. — The investigation of the 

 citrus mealy bug was continued for the most part along the lines indi- 

 cated in the last annual report, resulting in the demonstration of suc- 

 cessful control. Additional experimental work with hydrocyanic- 

 acid gas has been in progress, and a manuscript has been prepared as 

 a concluding report on this method of controlling scale insects on 

 citrus trees. Incidentally other insects affecting tropical and sub- 

 tropical fruits have been under observation. 



Citrus-fruit insects in Florida. — Investigations have thoroughly 

 demonstrated the practicability of controlling the citrus white fly 

 in Florida at a nominal cost by the proper use of sprays as recom- 

 mended. It has been demonstrated that the rust mite can be con- 

 trolled by the use of sulphur at the proper season, thus eliminating 

 the injuries from this pest commonly referred to as "shark skin," 

 " silver scurf," " buck skin," or " russety fruit." Other insects injur- 

 ious to tropical and subtropical fruits have been under observation. 



Citrus-fruit insects in Louisiana. — The investigation of citrus- 

 fruit insects in Louisiana, which has been in progress for some- 

 thing over two years, has been suspended temporarily on account of 



