THE IMPORTED ELM LEAF-BEETLE. 13 



fight this pest iu winter time, with a view of preventing its ravages the subsequent 

 season, will prove fruitless. A large proportion of the hibernating beetles doubtless 

 perish, since the insect is comparatively scarce in the earlier part of the season. 



(4 and 5) The beetles fly as soon as spring opens, and we have observed the first 

 larvae early in May,* in Washington, D. C, or some time after the elm leaves are fully 

 developed. The ravages of the insect begin to be apparent with the second genera- 

 tion of larvae, which appear in June. 



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 

 pupae, which in the latter part of August were to be found under the trees, wen; 

 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 riatynusr puncti- 

 formis and Quedius 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. rufilabriz) 

 feeds upon the eggs of the Galeruca ; Eeduvius novenarhis 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 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 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 larvae down onto 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 

 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 between the earth and the 

 trunk, enables us to kill vast numbers of the pupae and transforming larvae 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 larvae 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 

 larvae in their descent from the tree. Troughs, such as are used for canker-worms, 

 tarred paper, felt hands saturated with oil, are all good and the means of destroying 

 large numbers. Care must bo taken, however, that the oil does not come iu contact 

 w T ith 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 larvae let themselves drop down direct from the tree and 

 thus escape destruction. 



In conclusion we would remark that it is highly probable that ryrethrum powdei 

 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 he mixed in water. There is, however, no danger in the 

 judicious use of the arsenical liquids upon shade trees. 



* Some years, in Washington, it is the end of May before any larva- hatch, and the 

 time varies, of course, with latitude and season. 



