THE AMERICAN ENTOMOLOGIST. 



291 



NOTES ON THE IMPORTED ELM LEAF-BEETLE. 



HV IHE KDITOR. 



.\neiU Galcrtica xanthoiiif/u-na wliich is liccom- 

 irift more destructive each successive year to tlie 

 shade elms in our own northern towns, a corres- 

 pondent mentions the following facts : 



(1) "The trees are not all attacked at the same 

 lime, but the insect seems to break out from a 

 centre, gradually destroying the more remote 

 trees, so that isolated trees remain comparatively 

 free." 



(2) " .Vfler applying a band" (saturated with 

 tisli oil, petroleum, etc.) "to some trees which 

 were about half denuded, I found hundreds of 

 the worms stopped both in ascending and de- 

 scending the trees." 



He also propounds the following query : 



(3) Do the beetles hybernate in the ground so 

 that thev can be poisoned, or are they perpetuat- 

 ed only by the eggs on the trees? 



Allow me to add the following subjects for in- 

 vestigation as necessary to the devising of proper 

 remedies against this foreign invader. 



(4) How soon do the insects appear in the 

 Spring, how rapidly do they propagate, and what 

 time is passed in each stage of development? 



(5) Are the larvae and beetles eaten by insect- 

 ivorous birds, or are they protected by offensive 

 secretions as is the case with Doryphom lo-liiic- 

 a/a, Orgyin leucostigma, and several other nox- 

 ious insects? 



(6) What proportion of the brood hybernates, 

 and in what stage, pupa, or perfect insect? and 

 where ? 



If the inaterials for furnishing answers to these 

 questions are not yet within your reach, will you 

 kindly direct the attention of some of your 

 trusty observers to the subject, so that persons 

 interested in the preservation of the shade trees 

 which are so justly esteemed, may be properly 

 instructed as to the measures to be adopted dur- 

 ing the ne.xt summer. Very truly yours, 



J, L. LeConte, Phila, Pa. 



Though the above inquiries were re- 

 ceived from our esteemed correspondent 

 some titne since, we employ them as a ready 

 means of giving our experience with the 

 beetle in question. 



For the benefit of the general reader it 

 may be remarked that the natural history 

 of this Elm leaf-beetle is quite similar to 

 that of the well-known Colorado potato- 

 beetle and of the Grape-vine flea-beetle 

 both of which have been treated of in the 

 columns of this magazine. The only de- 

 viation in the Elm leaf-beetle is in the 

 mode of jntpation which rarely takes place 

 in the ground, unless this be very friable, 

 but at the base of the tree or under any 



shelter that may present itself near the 

 trees, such 3s old leaves, grass, etc. 



(li The phenomenon here described is 

 doubtless due to the gradual increase in 

 spring from one or more females. 



(3 and 6) Like most, if not all, Clirysom- 

 elidit, the Elm leaf -beetle hibernates in the 

 perfect state. As places suitable for hiber- 

 nation abound, any attempt to successfully 

 fight this pest in vs^inter time, with a view of 

 preventing its ravages the subsequent sea- 

 son, will prove fruitless. A large propor- 

 tion 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 larvas early in May in Washington, D. 

 C, or sometime after the Elm leaves are 

 fully developed. The ravages of the in- 

 sect begin to be apparent with the second 

 generation of larvae which appear in June. 



In 1878 we made many notes and ex- 

 periments on the species, and the develop- 

 ment of the third and most injurious gener- 

 ation occupied about one month. The 

 numerous pupce which in the latter part of 

 August were to be found under the trees 

 were mostly destroyed that year, partly by 

 continuous hot weather prevailing at the 

 time, partly by the many enetiiies of the 

 insect. Atnong these there are : Platyinis 

 pinutiformis and Quedius molochinus which 

 feed on the full-grown larva; when these 

 retire for pupation, and also on the pupae. 

 The larva of a Clirysopa (probably C. ru- 

 filabris) feeds upon the eggs of the Galer- 

 uca ; Rediivius noveiiarius sucks both bee- 

 tles and larvae on the leaves, while Mantis 

 Carolina preys upon the beetle. Of the 

 numerous other insects found among the 

 pupje under the trees, e. g, Tachyporus jo- 

 cosus, sundry spiders, myriapods, etc., sev- 

 eral are doubtless enemies of the Galenica, 

 though we have as yet no proof of the 

 fact. Many birds were observed on the 

 trees infested by the beetles, but the En- 

 glish Sparrow, which was the most nutner- 

 ous, did not feed on the insect in any stage 

 of growth. 



The only method of warfare against this 



