12 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



Mr. Glover regarded the pupa state as the most favorable in which 

 to kill the insect, as it can then be easily crushed or scalded. Con- 

 cerning the tobacco treatment he adds that "syringing the trees with 

 strong tobacco water lias been tried with some good effect, but the 

 larvse not touched by the fluid are merely knocked down by the concus- 

 sion, and, if nearly ready to change into pupae, effect their transforma- 

 tion where they fall." 



In this connection we cannot do better than quote what we published 

 in 1880* in reply to certain statements by Dr. J. L. Le Oonte, as fol- 

 lows : 



Anent Galeruca xanthomelcena, which is becoming more destructive each successive 

 year to the shade elms in our northern towns, a correspondent mentions the following 

 facts : 



1. The trees are not all attacked at the same time, but the insect seems to break 

 out from a center, gradually destroying the more remote trees, so that isolated trees 

 Temain comparatively free. 



2. After applying a band (saturated with fish-oil, petroleum, &c.) to some trees 

 which were about half denuded, found hundreds of the worms stopped both in ascend- 

 ing and descending the trees. 



He also propounded the following query: 



3. Do the beetles hibernate in the ground, so that they can be poisoned, or are they 

 perpetuated only by the eggs on the trees : 



Allow me to add the following subjects for investigation as necessary to the devis- 

 ing 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 larva? and beetles eaten by insectivorous birds, or are they protected by 

 offensive secretions, as is the case with Doryphora 10-lineata, Orgyia leucostigma, and 

 several other noxious insects ? 



6. What proportion of the brood hibernates, and in what stage, pupa or perfect 

 insect, and where? 



If the materials 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 during 

 the next summer. 



Very trul v, yours, 



J. L. Le CONTE, 



Philadelphia, Fa. 



The above inquiries were received from our esteemed correspondent some time since, 

 and we employ them as a ready means of giving our experience with the beetle. 



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- 

 heetle and of the Grape-vine Flea-beetle. The only deviation in the Elm Leaf-beetle 

 is in the mode of pupation, 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 as old leaves, grass, &c. 



(1) 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, Chrysomelida', the Elm Leaf-beetle hibernates in tire 

 perfect state. As places suitable for hibernation abound, any attempt to successfully 



* American Entomologist, December, 1880, p. 291. 



