THE IMPORTED ELM LEAF-BEETLE. ‘ 17 
kinds of injury ; first, that directly from the eating by the insect; sec- 
ond, that which follows indirectly from the deleterious effects of the 
poison on the plant, for its caustic effect is much greater where the 
leaves have been so gnawed that the poison comes in contact with the 
sap. 
Treatment with London purple.—Already early in June the insect ap- 
pears plentiful. On June 7, 1882, it was at work on all the trees, and 
its clusters of eggs were numerous beneath the leaves. Some of the 
trees had half of the leaves considerably gnawed and perforated by 
larve of all sizes, and by the adults. At this date fifteen trees, consti- 
tuting the south part of the grove, were treated. 
Preparation of the Poison.—London purple (one-half pound), flour (3 
quarts), and water (barrel, 40 gallons) were mixed, as follows: A large 
galvanized iron funnel of thirteen quarts capacity, and having a cross- 
septum of fine wire gauze, such as is used for sieves, also having verti- 
eal sides, and arim to keep it from rocking on the barrel, was used. 
About three quarts of cheap flour were placed in the funnel and washed 
through the wire gauze by water poured in. The flourin passing through 
is finely divided, and will diffuse in the water without appearing in — 
lumps. The flour is a suitable medium to make the poison adhesive. 
The London purple is then placed upon the gauze and washed in by the 
remainder of the water until the barrel is filled. In other tests the 
flour was mixed dry with the poison powder, and both were afterward 
washed through together with good results. It is thought that by mix- 
ing in this way less flour will suffice. Three-eighths of a pound of Lon- 
don purple to one barrel of water may be taken as a suitable percent- 
age. Three-eighths of an ounce may be used as an equivalent in one 
bucketful of water. The amount of this poison was reduced to one- 
fourth ofa pound to the barrel with good effect, but this seems to be the 
minimum quantity, and to be of value it must be applied in favorable 
weather and with unusual thoroughness. With one-half or three-fourths 
of a pound to the barrel, about the maximum strength allowable is at- 
tained, and this should be applied only as an extremely fine mist, with- 
out drenching the foliage. 
Effects of the Mixture.—The flour seems to keep the poison from tak- 
ing effect on the leaf, preventing to some extent the corrosive injury 
which otherwise obtains wher the poison is coarsely sprinkled or too 
strong. It also renders the poison more permanent. On the leaves, 
especially on the under surfaces, the London purple and flour can be 
seen for several weeks after it has been applied, and the insect is not 
only destroyed, but is prevented from reappearing, at least for a long 
period. By poisoning again, a few weeks later, the insect is deterred 
with greater certainty for the entire season. By being careful to ad- 
minister the poison betore the insect has worked, and, above all, to 
diffuse the spray finely but not in large drops, no harm worth mention- 
17527—Bull. 10 2 
