Sucking Insects 141 
showing variations from ten cents to ten dollars per tree.! 
Of the trees of Springfield, Mass., 16,000 were sprayed at 
an average cost of twenty- asthe 
nine cents. ‘This cost was : 
reduced in Saratoga, for 
5,067 trees of twenty to 
eighty feet in height, to 
seventeen and a quarter 
cents, and in Brooklyn, with Fic. 55. — ‘‘Vermoral” spray nozzle. 
steam apparatus for 8,712 trees, to twelve cents per tree, 
and this may be still further reduced by perfecting the 
apparatus and the organization. With hand apparatus, 
the cost for spraying trees up to forty feet in height may be 
as many cents as there are feet in height, but after that it 
increases more rapidly with the height. 
It is hardly practicable for each tree owner in a city, town, 
or village to provide himself with a spraying outfit, but 
every city, town, or even village can afford to supply an 
apparatus which would serve the entire community and, 
either at public expense or by codperative effort, all trees 
could be sprayed cheaply, and in a few years the insect 
question would be easy to take care of, if there is also co- 
operation in exterminating those insects which cannot be 
readily reached by poison. 
Sucking Insects. As stated before, these poisons are 
effective mainly with those biting insects which devour 
their food. They are not effective, or only partially so, 
with scale-insects, plant-lice, borers, as well as Curculios, 
chinch-bugs, etc., and all other kinds that suck the sap of 
the plants. These are best reached by a kerosene or soap 
emulsion, also applied by spraying, but in such a manner 
that the insect is struck, for they act by contact. 
1 Reported by A. H. Kirkland in The Shade-tree Insect Problem. 
