10. 
11. 
12. 
13. 
14, 
15, 
free~tailed bat, Molossus major, and less than one-fifth of the 
greater free-tailed bat, Molossus rufus. Both had approximately 
1:1 sex ratios. 
There was evidence that M. major has only one breeding cycle per 
year and some indication that M,. rufus may produce two generations 
annually. 

Application of a chlorinated hydrocarbon insecticide inside the 
enclosed roof spaces can be extremely difficult or even impractical 
both from a physical and a safety standpoint. The method finally 
adopted was conditioned by the space available, toxicity of the 
chemical used and the production of a suitable residue. 
A satisfactory method for applying insecticides in the form of 
wettable powders or pastes has been outlined for particular types 
of houses. Basically, this consisted of a conventional high- 
volume, power-driven sprayer with hose line and jet long enough 
to reach the side of the roof space furtherest from the escape 
trap door. 
For successful eradication of house bats, it is essential that the 
application be thoroughly carried out with no avenues for entrance 
or exit left unsprayed, 
D.D.T. acted more as a toxicant and B.H.C, more as a repellent to 
bats. 
Based on factors of economy and human safety, and also with a view 
to retaining as far as possible the beneficial attributes of these 
bats, the following repellent spray (rather than a toxicant) is 
recommended for bat control, especially in small, inaccessible 
roof spaces: one pound of B.H.C, 50% wettable powder to one gallon 
of water, However, where it is advisable to exterminate the bats, 
especially in large roof spaces, the substitution of D.D.T. for 
B.H.C. at the same dosage rate is preferred. 
If the spraying has been successfully carried out, the population 
of live bats can be expected to fall to zero by the end of three 
to four weeks from the application of either of these treatments. 
Information on the residual effectiveness of these insecticides 
is not complete but a period of at least one year is indicated with 
D.D.T. in large roof spaces and there is every possibitity that it 
may be effective for a longer period. B.H.C. is less residual, 
but in small roof spaces may be effective up to one year. 
As each building presents its own bat problem, due to diverse 
methods of construction, species of bat and locality, any method, 
15 

