Melanose infestation serious enough to cause economic damage was 

 not found in snail groves from 1946 to 1948 (Griffiths, 1949). Grif- 

 fiths speculated as to the possibility that the snails may eat the 

 spore normally found on the tree trunk. 



Effects on yield . Griffiths (1949) in a study of the effect of the 

 snail on yield production compared to nonsnail trees was unable to show 

 an increase or decrease in production costs or yield in the groves, 

 Muma and Selhime (1963) considered the purple scale, Florida red scale, 

 Chaff scale, Glover scale, dictyospermum scale, citrus rust mite, Texas 

 citrus mite, and citrus red mite on snail and nonsnail trees. They 

 reconfirmed Griffiths' findings that no difference could be found from 

 snail versus nonsnail trees. Sprayed plots, however, maintained lower 

 infestations than the unsprayed snail plots with exceptions of Florida 

 red scale and citrus red mite. Muma and Selhime (1963) also found that 

 sprayed plots produced a higher quality fruit with a higher yield than 

 the unsprayed acreage. 

 Citrus Rust Mite 



The citrus rust mite, Phyllocoptruta oleivora (Ashmead), is con- 

 sidered a serious pest in all humid citrus growing regions of the world 

 (Delucchi, 1975). This species was introduced into the Western Hemisphere 

 from Southeast Asia (Yothers and Mason, 1930). The citrus rust mite be- 

 longs to the family Eriophyidae. It is tetraoodili having only four 

 legs located anteriorly near the mouth. The eriophyids characteristi- 

 cally have elongated bodies annulated with small spines or furrows giv- 

 ing a segmented appearance (Krantz, 1975). A complete generation can 

 be completed in six to eight days during warm seasons in subtropical 

 regions (Delucchi, 1975). 



