ENCLOSURE TO PART IV. a 
prepared to recommend this method of control. As a whole, the 
results obtained have been most discouraging. I might add that our 
laboratory experiments on the effect of calcium arsenate on the larva 
of the Sudan bollworm seem to indicate that this poison has no effect, 
in that the larvee reject the poisoned rind of the cotton boll. 
TraPPING ADULTS. 
No experiments have been conducted along this line of insect 
control. I certainly think that this method of control is worth serious 
consideration. I have found that one female moth of the Sudan boll- 
worm lays nearly 500 eggs. 
HAND-PICKING AND COLLECTING LARVAE IN THE FIELD. 
An experiment on stripping the cotton plants, at a certain date 
when the infestation seemed to warrant it, of all squares and bolls 
(infested and sound), and another similar experiment followed by a 
dusting with calcium arsenate were conducted last season. The 
results were negative in each case. 
An experiment on picking the flared squares was also tried. This 
also gave negative results. 
To find out what percentage of the flared squares contained live 
bollworm larve, counts were made at a certain place last season. It 
was found that 319 of the bollworm-punctured flares (those fallen 
and on the plant) had live Sudan bollworm larve in them, that none 
contained American bollworm larve, and that 1 or 29 contained 
larvee of spiny bollworm. During cool or wet weather, a higher 
percentage of live larvee of the Sudan bollworm stayed in the flares. 
The mortality of larvee in these fallen flares was not worked out but it 
was found that the larger larve could live for a considerable time in 
the larger fallen bolls. With us, labour is too high to make this 
method of control practical; and, in any case, it appears that the 
results obtained do not warrant its use as a control measure. 
Trap CroprING. 
Only observations have been made on the use of maize as a 
trap-crop for the American bollworm. It has been noticed that, in 
some Instances, American boll worm attacks on cotton have followed 
the *“ hardening off * of the maize crop. No direct experiments have 
yet been conducted. 
Crose SEeasow. 
Few, if any, cotton growers in the Union of South Africa have 
attempted to apply a strict close season to their programme in cotton 
culture. As a rule, it only occurs when brought on by frosts or when 
pickings cease early in the winter. If connected with autumn or 
winter ploughing, I think it would have a very beneficial effect. With 
us, a close season is so closely linked up with the establishing 
(planting) of the following season’s crop that it seems inadvisable to 
enforce it at present. Hardships might be imposed unless the matter 
was carefully studied. However, in principle, I am in favour of a 
close season, and I think that the subject should receive careful study. 
The following conclusion was adopted : — 
That, although a great deal of experimental and investiga- 
tional work has been done on Sudan, American, and Spiny Boll 
Worms, this Section is not in a position to make any general 
recommendation. No economic means of control have yet been 
devised, and we are of opinion that further investigations are 
desirable and necessary. 
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