15 
eggs were seldom deposited on the young leaves that were appearing 
after the poison was applied, but were attached to the developed leaves, 
and here the larve generally got the poison to prevent their attack 
upon the aftergrowth. Still the young leaves became perforated to 
some extent. The adults, which fly from tree to tree, appeared plenti- 
ful without much interruption throughout the season, and often several 
could be seen feeding on each tree. Possibly many of these may have 
become poisoned before depositing the eggs. 
The efficiency of London purple being established, “it will generally 
be preferred to other arsenicals, because of its eieaniiegy: better. dif- 
fusibility, visibility on the foliage, ete. As the effects of the poisons 
commonly do not appear decidedly for two or three days after their 
administration, the importance of the preventive method of poisoning 
in advance can not be too strongly urged. As the effect ts slow in 
appearing, impatient parties will be apt to repoison on the second 
or third day, and thus put on enough to hurt the plant when the effect 
does come. Much depends on dryness or wetness of the weather, but 
good effects may be expected by the third or fourth day. 
London purple seems to injure the plant less than Paris green. 
Treatment with Paris Green.—In 1885 the Paris green was first applied 
on the 29th of May, at which date the eggs were extremely abundant 
and hatching rapidly on the leaves. Paris green, flour, and water were 
mixed by the means previously employed with London purple and 
already described. The mixture was applied to the north part of the 
same grove of elms. Thus far experience shows that the Paris green 
is effective against the insect, but that this poison injures the plant more 
than does the London purple. 
Three-fourths of a pound of Paris green to a barrel (56 or 40 gallons) 
of water, with 3 quarts of flour, may be regarded as a poison mixture 
of medium or average strength for treating elms against these beetles, 
and the indications thus far are that the amount of Paris green should 
not be increased above 1 pound or be diminished much below one-half 
a pound in this mixture. To a bucketful of water three-fourths of an 
ounce of Paris green may be used. The action of this poison is slow 
but severe, and varies much with the weather. Thus far the results of 
tests have been varied so much by the weather and different modes of 
‘preparation and application that they will be repeated. When used 
strong enough to cauterize the leaves the poisonous action upon the 
plant may be observed to continue for several weeks. 
Mechanical Means of Applying the Poison—W hen many trees were to 
be sprayed a cart or wagon was employed to haul the poison in a large 
barrel provided with a stirrer, force-pump, skid, etc. The following 
brief account of the skid, mixer, barrel, and pump may be reproduced 
here from our last ental Report: 
The skid is a simple frame to hold the horizontal barrel from rolling, and consists 
of two pieces (PI. 1, Fig. 3 aa) of wood, about the length of the barrel, and in section 
about 3 by 4 ce joined parallel, apart from each other, by two cleat bb. The 
