PREVIOUS STUDIES ON CONTROL METHODS 
A certain amount of work has been done elsewhere where the same 
problem exists (Silver et al. 1935, 1951), but there the emphasis was 
mainly placed on the use of dangerous fumigants. These included the 
burning of sulphur or the evolution of hydrogen cyanide gas which are 
extremely hazardous not only to the operators but also to the house 
dwellers and in addition give only temporary relief, since there is no 
residual effect. 
Less dangerous materials, such as naphthalene and paradichloro- 
benzene, have also been advocated, but on test in Trinidad were found 
to vaporize too rapidly due to the high temperatures and humidities 
prevailing on this island, For instance, roof space conditions were 
as follows for the period January 13-19, 1959: Maximum temperature 
of 104° F.; minimum temperature of 67° F.; humidity, 55-100%. Where 
the bats actually roost would in fact show, at times, greater daily 
extremes over a longer period, where temperature ranges from 60°-135° F., 
have been recorded in other investigations. This possible 75° fluctu- 
ation within a 24-hour period has caused metal roofs to contract and 
expand so that "bat proofing" plugs of wood, concrete, plaster, or 
other materials are rendered useless due to the cracks and spaces re- 
sulting from this exaggerated roof movement, 
A number of local bat repellents have also been tried, such as 
hanging spiky lime twigs where bats congregate, burning dried pepper 
pods, erection of lights (both electric and kerosene) frequently used 
in combination with owl or hawk wings to produce moving shadows, and 
finally spreading out pineapple skins, These methods have all met 
with only partial or temporary success, Sticky and chemical bird 
repellents have also been advocated by Scott (1958). 
Two specific examples of the use of insecticides may also be 
cited as they were tried out in Trinidad. BHC sprayed from high- 
volume pneumatic machines is reported by Robertson (1952) to have 
eliminated bats from houses and given a residual effect for one year, 
De la Motte (1958) has reported that dieldrin applied through a low- 
volume power-operated sprayer eliminated bats from cocoa drying sheds, 
though the bats then controlled would probably have been of different 
species from the normal house bats in Trinidad. A final reference 
came to our notice during the compilation of this paper when, although 
not advocating the wholesale destruction of bats, Eads (undated) claimed 
that 50% D.D.T. had been used with some success. 
