Chapter XIL 

 INSECTS INJURIOUS TO THE HACKBERRY. 



By C. V. Riley. 



The Hackberry is one of the most characteristic trees in our American 

 silva. What is said of the forms growing in Missouri in my sixth report 

 on the insects of Missouri (1874, p. 137) will apply to other parts of the 

 country in the same latitudes — in fact, throughout its range. 



Two tolerably constant forms are easily recognizable: 1. (occidentalis Linn.) 'witli 

 broad, ronghish, sbarply serrate leaves, j)urple-black drupes, and rather pale bark, 

 which on the trunk is rough and strongly cleft so as to look as if hacked. 2. {missis- 

 sijypiensis Bosc.) with smaller, narrower, darker leaves, less serrate and often entire 

 yellow drupes, and darker bark, the trunk appearing knotty. A third form (crassi- 

 folia Lamk.), having more the aspect of TJlmus, occurs less frequently. It is much 

 like occidentalis, but with more supple limbs and rougher, thicker leaves, which, 

 when plucked, wilt more rapidly than do those of other forms. Botanists differ as 

 to whether these forms are specific or varietal. Dr. Gray refers them all to Occident 

 alis, and, as intermediate varieties are found and the seedlings from the same tree are 

 exceedingly variable, this seems the proper course. But Professor Planchon, who 

 has monographed the genus, considers 1 and 2 good species, and the third doubtful. 



In the report already alluded to (pp. 136 et seq.) under the head of 

 " Hackberry butterflies," original accounts, with illustrations, will be 

 found of the life-histories of two of our handsomest North American 

 butterflies, which, so far, have been found to feed in the larval state 

 exclusively on Hackberry. They are there treated of under the names, 

 "Eyed Emperor" {Apatura lycaon), and "Tawny Emperor" {A. herse 

 Fabr.), and the synonymy of the species is fully discussed and the 

 reasons given for preferring the names of Boisduval and Le Oonte 

 {Apatura celtis and Apatura clyton). As the reasoning there has since 

 been confirmed by the adoption of the latter names, both by Mr. W. 

 H. Edwards and Mr. S. H. Scudderin their catalogues, these names will 

 be used in the present instance.* 



* Led by Mr. Scudder's previous writings to adopt the Fabrician names, I never- 

 theless took some pains to get at the real facts, and concluded, after considerable 

 correspondence, that there was no cause to change the conclusions which I had pre- 

 viously expressed, that we have but two species of Apatura in the United States, viz : 

 A. hjcaon Fabr. = celtis Boisd. — alicia Edw.; and A. herse Fabr. = clyton Boisd. = 2^j-o- 

 serpina Scudd. But I admitted that there would ever hang a certain doubt about 

 herse, and that had I the paper to write over again I would use the Boisduval names, 

 because I believe that science is better advanced by the use of names based upon 

 descriptions of the living animals rather than by unearthing such as are drawn from 

 pencil (and often faulty) imitations, and which admit of doubt and dispute. "In 



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