Insects and Insecticides. 
33 
It would require considerable space to give full directions for 
the fumigation of orchard trees, and, as there is little likelihood that 
such fumigation will be called for in Colorado for some time 
to come, I shall not take space to describe the process here. Those 
specially interested can obtain bulletins giving full directions from 
the Department of Agriculture, Division of Entomology, Washing¬ 
ton, D. C. Full directions can also be obtained in a book entitled 
“Fumigation Methods,” by W. G. Johnson, and published by 
Orange Judd Co., New York. Figs. 16 and 17 are from this book. 
SUBSTANCES THAT REPEL 
There are a number of substances that are more or less useful 
for the purpose of driving insects away from places where they 
would do harm if unmolested. I give below a few of the most 
important. 
30. NAPTHALINE, GUM-CAMPHOR, AND MOTH BALLS. 
Napthaline crystals are much used in insect boxes and in boxes 
or trunks where furs, feathers or woolen goods are kept, for tne pur¬ 
pose of keeping out insects that feed on these animal products. It 
is probably the best single chemical that can be used for this 
purpose. Gum-camphor is also much used for the same purpose 
and moth-balls are a combination of these two volatile substances. 
These materials cannot be used to kill insects, but only to repel 
them. 
31. TOBACCO. 
Tobacco, in the form of dust, or otherwise, is often used for the 
same purpose as the preceding, but to be effectual must be used 
quite freely. 
32. ASHES. 
Ashes, particularly from wood, are frequently used to dust 
upon plants after a rain or while the dew is on and often result in 
the insects disappearing. Particularly is this true in case of flea- 
beetles and the cucumber beetle when feeding upon leaves. Ashes 
do not kill the insects, but they make the food distasteful, so the 
insects are driven to other plants. 
33. LIME, PLASTER, AND ROAD DUST. 
These substances are also used like ashes as repellents, but are 
of little or no use for the destruction of insects. 
INSECT TRAPS. 
There are many methods of trapping and destroying insects. 
One of the most common is the use of bright lights exposed 
at night. 
