102 BULLETIN 536, U. S. DEPARTMENT OF AGRICULTURE. 



and cheaply protected. Coverings of cheese-cloth are often matted 

 against the fruit by rains, thus making it possible for the female fly 

 to oviposit in the fruit. The practice of covering mangoes with paper 

 bags will afford protection to certain scale insects and permit them to 

 develop and ruin the fruit. 



Frequently all the fruits on a tree may be seen inclosed in paper 

 bags. While this method of covering each fruit gives protection from 

 the fruit fly, it involves much labor and patience and its practicability 

 can only be determined by the value placed upon the fruit by the 

 owner. So severe is fruit-fly attack in Hawaii that this method, in 

 some one of its many modified forms, is the only remedy if fruits are 

 to be brought to maturity uninfested. 



CLEAN CULTURE. 



Clean culture in its broadest sense includes not only the detection, 

 collection, and destruction of all infested fruits but also the elimination 

 of useless or unnecessary host trees or shrubs. In some one or all of 

 its phases it has been recommended and practiced in every country 

 where the fruit fly is a pest, and in each one of these countries the 

 lethargy displayed by a majority of the people, no matter how much 

 they have regretted their losses, has rendered the clean cultural 

 methods inefficient. The effectiveness of clean culture depends upon 

 many factors, of which cooperation among property owners, honesty 

 on the part of inspectors, climatic and host relationships, the to- 

 pography of the country, and a thorough knowledge of host fruits 

 on the part of the director are the most important. Clean culture 

 in the Bermudas, where conditions are exceptionally favorable for 

 stamping out the pest, was rendered less effective, up to 1914, be- 

 cause there was lacking a thorough knowledge of the complete list 

 of host fruits subject to infestation. The fruit fly has been stamped 

 out at Blenheim, Napiers, and Davenport, New Zealand, and at 

 Launceston, Tasmania, by the application of such clean cultural 

 methods as the destruction of the fruits and the treatment of the soil 

 beneath the trees with kerosene immediately after the discovery of 

 the pest. The only other recorded instance of success attained as a 

 direct result of clean cultural methods is that of the orange growers 

 of the Biackall Range, in Queensland, Australia. These growers held 

 a council and voted to grub out every kind of fruit tree except the 

 orange, which was their staple crop. As a result of this drastic 

 remedy the fly had nothing in which to breed during nine months of 

 the year in this section, and therefore ceased to be a pest. 



The clean-culture campaign instituted by the Hawaiian Board of 

 Agriculture during the fall of 1911 and continued by the Federal 

 Bureau of Entomology from October, 1912, until April, 1914, was 

 unsuccessful from its inception, since it did not protect the fruit 



