
7 
weeds which are secondary food plants of tobacco insects, such as 
Solanum nigrum, Solanum carolinense, and Datura stramonium, act 
simply as concentrators and multipliers of the tobacco insects, so that 
the insects are already in force about the margins of the fields, ready 
to transfer their attentions to the young and succulent tobacco plants 
after they have been planted. Frorn this it is plain that, if the mar- 
gins of the fields are kept free from such plants, the insects will not 
have as good a start, and will not be present in such great numbers. 
It also follows that, if a few attractive weeds are left in clumps, the 
flea-beetles and other tobacco insects of the immediate vicinity will 
concentrate upon these few weeds, where they can readily be killed, 
either by the application of an arsenical poison, if they are gnawing 
insects, or of a kerosene emulsion, if they are sucking insects. 





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Fia. 3,—Leaf spots of old tobacco leaf—slightly reduced (original). 
Where preliminary work of this nature has been neglected, and it 
becomes necessary to treat the tobacco flea-beetle in the tobacco field, 
we are prepared to heartily recommend the use of arsenical poisons. 
Small as the insect is, and much as its initial work looks like the 
puncture of a beak rather than the nibbling of a pair of jaws, it is a 
true biting or gnawing insect; therefore, if the leaves be treated, even 
with a minute quantity of an arsenical poison, the insect will be 
reached by it in the act of eating the leaf, and will be destroyed. 
This is not as satisfactory a means of killing the insect as the pre- 
ventive mentioned above, for the reason that, in order to get its dose 
of the poison, the insect must damage the leaf to a certain extent, 
and as there is a constant succession of new beetles, the leaves will 
become damaged more or less, even though the insects be destroyed; 
