THE WHITE COFFEE-LEAF MINER. 603 
leaves would be lost, if whole branches were cut off. I think it 
would be better to pick off all the infested leaves, and burn them, 
leaving the healthy leaves to support the tree. Guérin says [Mém. 
etc., p. 19] that ‘ the epoch which it would seem ought to be the 
most favorable for this operation would be that which immediately 
follows the winter season, or that during which the temperature is 
the lowest, because the larva finds itself then as it were benumbed, 
and cannot be transformed into a moth until the return of a softer 
temperature.” The time appointed for picking off the leaves 
might be, for the obvious purpose of saving labor, that at which 
the smallest number of old leaves remain upon the trees, if there 
is any such time. If the leaves were picked at such time as to 
take the greatest number of larvæ when they were about two 
weeks old, it would not be difficult to select them, as the size of 
the blotches would make them very noticeable. 
I have made a theoretical estimate of the expense which would 
be incurred in picking off the leaves as I recommend, and of the 
relative increased yield of coffee which would result on a planta- 
tion of given size. Testing this theory by the numerical data 
given to me by Dr. Christovao Corrêa e Castro, and making large 
allowances for unfavorable circumstances, I find that the expense 
would be more than met by the next year’s crop; but even if 
this should not be the case in the second year, it must be remem- 
bered that such a thorough and expensive war upon the insects 
never need be made more than once, and that with vigilance the 
trees could be kept in good order and the increased yield maintained 
continually afterwards. But vigilance must be exercised. One 
Picking would not entirely exterminate the insects, however thor- 
oughly it were done. The planters should also make experiments 
at all times, and seek other means of destroying not only this 
but all the enemies of their crops. They alone have the facili- 
ties for increasing and utilizing all the knowledge which can be 
guned upon these subjects. ; 
Another remedy which Guérin recommends is “to kindle fires at 
all points of the coffee-plantations, at the time when the moths 
begin to issue from their cocoons. It is well known that many 
insects, and above all the nocturnal Lepidoptera, are attracted by 
ight, and come whirling around a fire until they are burned there. 
Certainly a great number of individuals would be thus destroyed. 
At the same time, and to attain this object more promptly, lighted 
