Howes and Wells (1934) referred to it as an estivation period. During 

 estivation, a "mucous veil" of dried mucus seals the opening. The use 

 of the term estivation here is unfortunate since the closing off is 

 short term and may occur at any time of the year. 



Mature citrus trees six years old and older are the only ones from 

 which the snail can receive the proper abiotic conditions for survival 

 (Kramer, 1952). Cover crops were suggested by Kramer (1952) as a means 

 of increasing the shade and relative humidity in the grove undergrowth 

 for snail migration. He also suggested this would increase humidity in 

 the trees. 



Hunter (1964) discussed the ability of stylommates to maintain tem- 

 perature homeostasis by withdrawal into the shell. The migration of 

 snails toward a preferred temperature or habitat was discussed by Getz 

 (1959). He showed the snails possessed a temperature and humidity 

 preferendum. 



Calcium is necessary for development of snail shells. Experiments 

 on land snails in captivity show that the thickness and weight of the 

 shell is directly dependent on the amount of calcium in food supplied 

 (Boycott, 1934; Robertson, 1941). Some snail species are limited to 

 high calcium content soils (Boycott, 1934). 



Predators, parasites, and pathogens . Muma (1955) suggested 

 factors that cause mortality of D. dormani . Egg mortality was due 

 to desiccation and to small earthworms. Newly hatched snails were 

 preyed on by a predatory snail, Euglandina rosen Ferrusac. Additional 

 mortality was attributed to desiccation. Young snails were found to be 

 parasitized by two Diptera, Johnsonia elegans Aid. and Johnsonia sp. 

 probably frontalis Aid. Euglandina rosea also was found to prey on 

 young snails (Muma, 1955). 



