BUKEAU OF ENTOMOLOGY. 521 



fungous disease have been carried out probably in sufficient fullness 

 and detail, and the final reports covering these subjects are now in 

 press or practically ready for publication. Aside from the com- 

 pletion and reporting on these subjects, the chief work of the year 

 has been experimental testing and demonstration of the value of 

 different spray applications. The conditions of Florida cili'us culture 

 are such that very often gas treatment is too expensive, especially 

 with an insect such as the white fly, where reinfestation from neigh- 

 boring neglected groves is very easy. Hence the necessity of deter- 

 mining the most practicable and effective spray applications, which 

 are much cheaper, for a single treatment at leas-t, than h3^drocyanic- 

 acid gas fumigation. The principal insecticide washes experimented 

 with include (1) a considerable series of oil-soap emulsions made 

 Avith different brands of oil; (2) several of the commercial miscible 

 oils which are very similar in composition to the oil-soap emulsions; 

 and (3) sulphur washes. A good many other recommended mixtures 

 have also been tested, and the Florida grower has been protected in 

 this way from the purchase of worthless insecticides. It was hoped 

 that the insecticide work would be completed this season, but it has 

 not been possible to bring it to a conclusion, and another season's 

 work w'ill be required to finish the needed experimental tests. This 

 work has been conducted, in all cases where the mixture warranted 

 it, on a considerable scale, often over entire orchards, to give the 

 tests the greatest practical value. It seems pretty well demonstrated 

 that spraying will, under Florida conditions, be more generally 

 adopted in the future than control by fumigation. 



In a previous paragraph in this report, under the heading " Impor- 

 tations of useful insects," an account has been given of the sending 

 of an expert assistant in search of the original home and the natural 

 enemies of the white fly. This forms an integral and important por- 

 tion of the white-fly work. 



THE ORANGE THRIPS. 



The investigation of the orange thrips is still under way at Lind- 

 say, Cal., and has been extended to southern California, particularly 

 in the Riverside district, where the same or an allied thrips is causing 

 considerable damage. Control by cultivation and fumigation proved 

 unsatisfactory. The spray which has given the best results is a lime- 

 sulphur sol ut it 71 with a tobacco extract added. Three applications — 

 two in the spring and one in the fall — have resulted in saving from 

 20 to 60 per cent of the fruit. The work of the past fiscal year has 

 been a continuation of sjiraying tests modified from the results ob- 

 tained the previous year in connection with demonstration orchard 

 sprayings. More than 20 different spray tests are being carried out, 

 including, in addition to the sulphur washes, various soapy, oily, and 

 tobacco Avashes, a plat of 50 trees being used in each test, with suit- 

 able check trees left unsprayed. The season has not been altogether 

 favorable for these exj^orimental tests in that the thrips itself has 

 been less abundant, owing to climatic variation, than in previous 

 years, but it is expected that the work of the fiscal year 1912 will 

 fairly well demonstrate the best means of control by spraying. An 

 investigation has been marie of the situation at Riverside, and some 

 preliminary spraying experiments are under way. 



