14 
pal uses of arsenical poisons is for the control of the codling moth. 
Detailed information on the subject is given in Farmers’ Bulletins 
Nos. 247 and 283. The plum curculio is discussed in Circular No. 73, 
and leaf-feeding grape insects in Farmers’ Bulletin No. 284. Other 
publications relating to special insect problems are also available 
giving detailed directions for spraying. 
For leaf-feeding insects in general, such as the Colorado potato 
beetle, blister beetles, elm leaf-beetle, maple worm, and other forest 
or shade-tree caterpillars, the application should be made at the 
earliest indication of injury, and repeated as often as necessary. 
Fruit trees should mever be sprayed when in bloom, on account of 
the lability of poisoning honey bees or other insects useful as cross- 
fertilizers. 
There is no basis for the idea occasionally advanced that the fre- 
quent use of Paris green or other arsenicals on potatoes and other 
crops is injurious to the foliage or health of the treated plants. This 
matter has been fully tested, and the injurious results can always 
be accounted for by improper mixtures or applications. 
CARE IN THE USE OF ARSENICALS. 
It must be remembered that these arsenicals are very poisonous and 
should be so labeled. If ordinary precautions are taken, there is no 
danger to man or team attending their application. The wetting of 
either, which can not always be avoided, is not at all dangerous, on 
account of the great dilution of the mixture, and no ill effects what- 
ever have resulted from this source. With some individuals the arsen- 
ate of lead, when in strong mixture, affects the eyes, but this is un- 
usual, and, with a little care in spraying, the mist need not strike the 
operator at all. 
The poison disappears from the plants almost completely within 
twenty to twenty-five days, and even if the plants were consumed 
shortly after the application, an impossible quantity would have to be 
eaten to get a poisonous dose. To illustrate, in the case of the apple, 
if the entire fruit were eaten, core and all, it would take several bar- 
rels at a single sitting to make a poisionous dose (Riley), and with the 
cabbage, dusted as recommended above, 28 heads would have to be 
eaten at one meal to reach this result (Gillette). It is preferable, 
however, to use other insecticides in the case of vegetables soon to be 
eaten, and thus avoid all appearance of danger. 
INSECTICIDES FOR EXTERNAL SUCKING INSECTS (CONTACT 
POISONS). 
The simple remedies for this class of insects, such as soap, insect 
powder, sulphur, tobacco decoction, etc., are frequently of value, but 
need little special explanation. Some brief notes will be given, how- 
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