240 
Methods of Preventinrj and Cliecldncj 
not run like ordinary cart-grease made of animal fats. Care 
must be taken, as some of the compounds advertised have injured 
trees. Constant greasing, also, even with the most approved 
mixtures, is apt to injure the bark. It is well, therefore, to put 
the grease upon bands of grease-proof paper, as used by grocers, 
from six to eight inches wide. These can be fastened round the 
trees with bast or string.' 
For the attacks of caterpillars upon apple, plum, damson, 
pear, and cherry trees, sprayings with various compositions 
have been found useful. These are also of advantage as against 
the apple-bud weevil (AntJtonomns pomorum), the apple-sucker 
(Psylla mali),^ the American blight, or woolly aphis (Schizoneura 
lanigera), the Codlin moth, and other pests. 
The compositions employed in order to prevent and check 
the attack of destructive insects, or to clear them away alto- 
gether, should differ according to their various natures and 
habits. Thus, as has been well defined by Professor Riley and 
Dr. Packard,^ those which bite and eat the foliage or blossoms, 
as caterpillars and the larvfe of saw-flies and the larvae of beetles, 
are affected directly or killed by poisons applied to their food, 
while other classes of insects, such as Aphides and theCercopidae, 
living upon the sap of plants extracted by suction from the 
leaves or stems, are killed by a direct effect upon their bodies, 
or are starved out and prevented from reproduction by the un- 
pleasant or unwholesome surroundings occasioned by oily, sapo- 
naceous, bitter, pungent, or irritating applications. 
For example, caterpillars upon apple-trees would be poisoned 
by feeding on the leaves sprayed with solutions of Paris Green 
or London Purple. On the other hand, aphides, for instance of 
the hop plant, being covered as well as the leaves which 
they infest with spray from mixtures of soft soap and quassia, or 
of soft soap and paraffin oil, rapidly disappear. It has not been 
ascertained whether these act directly upon their bodies, or by 
making the host-leaves offensive and unbearable. 
"Washes are various ; one has been applied with much benefit 
in Kent for caterpillars and larvje of similar habits, consisting 
of— 
' Tlio Hon. Cecil T. Parker informs me that he h;is used vaseline with 
great advantage for banding fruit-trees. It costs 2|rf. to 3d. per lb., and re- 
mains sticky throuKliout the winter. 
^ The injury caused by this tiny insect has only been recently noticed, 
though, as Rliss Ormerod states, it is well known in Britain. Some barm has 
been caused by it this season in some apple orchards. 
" Finirth mid Fifth lte/)orlK of ilic United Statex Entomological Comniis.iion, 
188.3-1885; I8H()-18!K). I'ublished by the United States Department of Agri. 
culture, 
