10 THE IMPOETED ELM LEAF-BEETLE. 
In 1878 we made rnany notes and experiments on the species, and the development 
of the third and most injurious generation occupied about one month. The numerous 
pupa? which in the latter part of August were to he found under the trees were 
mostly destroyed that year, partly by continuous wet weather prevailing at the time, 
partly by the many enemies of the insect. Among these there are Platynus puncti- 
formis and Quedins molochinus, which feed on the full-grown larvae when these retire 
for pupation, and also on the pupae. The larva of a Chrysopa (probably C. rufilabris) 
feeds upon the eggs of the Galeruca, Eeduvius novenarius sucks both beetles and larva? 
on the leaves, while Mantis Carolina preys upon the beetle. Of the numerous other 
insects found among the pupae under the trees, e. g., Tachyporus jocosus, sundry spiders, 
myriapods, &c, 'several are doubtless enemies of the Galeruca, though we haveasySt 
no proof of the fact. Many birds were observed on the trees infested by the beetles, 
but the English Sparrow, which was the most'numerous, did not feed on the insect 
in any stage of growth. 
The only method of warfare against this pest recommended by European writers is 
to jar the larva? down on to sheets, and then in one way or another to destroy them. 
This may answer for young trees, but is then tedious and but partial. We found that 
the quickest and most satisfactory way of destroying the insect and protecting the 
trees was by the use of Paris green and water in the manner frequently recommended 
in these columus, and London purple will evidently prove just as effectual and 
cheaper. The syringing cannot be done from the ground except on very young trees, 
though a good fountain pump will tbrow a spray nearly 30 feet high. Larger trees 
will have to be ascended by means of a ladder and the liquid sprinkled or atomized 
through one of the portable atomizers, like Peck's, which is fastened to the body, and 
contains 3 gallons of the liquid. 
The mode of pupation of the insect under the tree, on the surface of the ground, 
beneath whatever shelter it can find, or in the crevices betweeu the earth and the 
trunk, enables us to kill vast numbers of the pupie and transforming larva? by pour- 
ing hot water over them. We found that even Paris-green water poured over them 
also killed. If the trees stand on the sidewalk of the streets the larva? will go for 
pupation in the cracks between the bricks or at the base of the tree, where they can 
also be killed in the same way. This mode of destruction is, take it all in all, the 
next most satisfactory one we know of, though it must be frequently repeated. 
(2.) We have largely experimented with a view of intercepting and destroying the 
larva? in their descent from the tree. Troughs, such as are used for Canker-worms, 
tarred paper, felt bands saturated with oil, are all good and the means of destroying- 
large numbers. Care must be taken, however, that the oil does not come in contact 
with the trees, as it will soon kill them, and when felt bandages are used there should 
be a strip of tin or zinc beneath them. The trouble with all these intercepting de- 
vices, however, is that many larva? let themselves drop down direct from the tree and 
thus escape destruction. 
In conclusion we would remark that it is highly probable that Pyrethrum powder 
stirred up in w^ater might be successfully substituted for arsenical poisons, but experi- 
ments in this direction have not yet been made. From experiments we have made 
with dry, unmixed powder, we found that it affects very quickly the larva, pupa, 
and the perfect insect, but in order to be applied on a large scale and on large trees 
the powder must of course be mixed in water. There is, however, no danger in the 
judicious use of the arsenical liquids upon shade trees. 
MORE RECENT EXPERIENCE AT THE DEPARTMENT. 
The more recent experience in the destruction of this Galeruca on the 
Department grounds may now be summed up, the experiments having 
been intrusted to Dr. Barnard. 
