BUREAU OF EXTOMOLOGY. 261 



insect control done in the State. This method of control has practi- 

 cally eliminated this mealybug from upward of 500 acres near Up- 

 land, Calif., and, in fact, over most of the district infested by this • 

 ineect, and for the first time in years the owners of these orchards 

 are able to sell their fruit in prime condition at the highest market 

 price. This method of control will be rapidly extended over the en- 

 tire infested district. 



In connection with the investigation of the two principal meal}^- 

 bng enemies of citrus plants in southern California, tlie parasitic and 

 l)redatory enemies of these insects have been further investigated as 

 also the symbiotic relations of these insects with the Argentine ant. 



Tlie dejpartment h.as cooperated with the California authorities in 

 the determination of the best metliods of exterminating the European 

 snail {liel'ix f'tsana) which has become established in a small canyon 

 or district near San Diego. As a result of this investigation and of 

 various conferences the method of control now lacing carried out by 

 the State is the burning over of the district with torches fed with 

 oil under pressure totally to destroy the vegetation. This snail was 

 possibly introduced by some foreigner familiar with its food value 

 in Europe, without thought as to it's tremendous possibility for harm 

 to cultivated crops. 



Citrus fruit i>jsects in Florida. — The work under this project 

 during the year has been largely limited to demonstrational work in 

 the aid of increased production."^ Spraying demonstrations have been 

 conducted Avidely throughout the State. A revised schedule for 

 fumigation and treatment of trees to prevent insect injury has been 

 worked out for the grapefruit, and a Farmers' Bulletin (Xo. 1011) 

 has been issued entitled "' The Woolly White Fly in Florida Citrus 

 Groves," Some special lines of investigation have had to do with 

 the stabilizing of insecticides especially where the only Avater avail- 

 able is obtained from deep wells containing a large percentage of 

 mineral elements which more or less affect the stability of certain 

 emulsions and other insecticides. The work in Florida has had par- 

 ticular relation to the citrus Avhite fiy, the rust mite, and the com- 

 mon Florida scale insects. The work in the control of citrus pests 

 in Florida has shown the greater availability of liquid sprays over 

 the fumigation methods commonly followed on the Pacific coast. 

 During the last two years, hov\'ever, considerable demonstration work 

 has been done with fumigation in Florida by a fjrivate concern-, the 

 results of which have been carefully examined by the expert of this 

 department as a protection to citrus growers and to determine that 

 any claims made are fully justified, 



IXVESTIGATIOXS OF INSECTS AFFECTING MAXGO, GUAVA, AVOCADO, AND 



OTHER SUBTROPICAL FRUITS. — The mango and avocado and other fruits 

 mentioned under this heading are being commercially developed on 

 a considerable scale in southern Florida. A station has been estab- 

 lished at Miami in cooperation with the Office of Foreign Seed and 

 Plant Introduction of the Bureau of Plant Industry of this depart- 

 ment to investigate the peculiar insect enemies of these fruits. _ Dae to 

 tlie proximity and commercial connections of southern Florida Avith 

 Bermuda, the West Indian Islands, and Central America, this region 

 is especially open to invasion by important fruit pests, and several of 

 these have" already gained entrance. One feature of the project, 



