10 THE IMPORTED ELM LEAF-BEETLE. 
In 1878 we made many notes and experiments on the species, and the development 
of the third and most injurious generation occupied about one month. The numerous 
pup which in the latter part of August were to be 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 punceti- 
formis and Quedius molochinus, which feed on the full-grown lary when these retire 
for pupation, and also on the pupw. Thelarva of a Chrysopa (probably C. rujilabris) 
feeds upon the eggs of the Galeruca, Reduvius novenarius sucks both beetles and larve 
on the leaves, while Mantis carolina preys upon the beetle. Of the numerous other 
insects found among the pupa under the trees, e. g., Tachyporus jocosus, sundry spiders, 
myriapods, &c., several are doubtless enemies of the Galeruca, though we have as yet 
no proof of the fact. Many birds were observed on the trees infested by the beetles, 
‘but the English Sparrow, which was the mostjnumerous, 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 larve 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 columns, 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 throw a spray nearly 30 feet high. Larger trees 
will have to be ascended by means of a ladder and the liquid sprinkled or atomized 
throngh 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 between the earth and the 
trunk, enables us to kill vast numbers of the pup and transforming larve by pour- 
ing hot water over them. We found that even Paris-green water poured over them 
also killed. Hf the trees stand on the sidewalk of the streets the larvze 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 
larve 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 larvie 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 water 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 Haye 
been intrusted to Dr. Barnard. 
