25 



THE YELLOW CANKEK WOKlil. 



(Hihernia Tiliaria, Harris.) 



(Order Lepidoptera. Family PnALiBNiD^.) 



[Feeding upon the leaves of Apple, Elm and various other trees 

 and shrubs ; a naked ten-legged span-worm of a yellowish color, 

 marked on the back with ten black lines.] 



During the years 1879 and '80 many orchardists in Northern Illinois 

 suffered severely from the attacks of a kind of Span-worm which many 

 persons supposed to be the common Canker-worm {Anisojyteryx vernata. 

 Peck.) In the month of June of the above years these insects appeared 

 in the orchards in such numbers that the leaves on the infested 

 trees soon presented the appearance of having been riddled with 

 shot; and the hazel-bushes in the adjacent woods were so infested 

 by them that by the middle of summer scarcely a whole leaf could 

 be found upon them. In the last named year (1880) I noticed that 

 many of these Span-worms had a number of raised white spots on 

 the anterior part of their bodies ; I examined many hundreds of the 

 worms, but could scarcely find one in fifty that did not have from 

 one to six of these spots upon it. These spots were, very probably, 

 the eggs of some parasitic insect. I enclosed in one of my breed- 

 ing cages several of these Span-wormp, each of which had a number 

 of these spots upon it, and supplied them with food until they en- 

 tered the earth for pupation ; but I did not succeed in obtaining 

 either moths or parasites from them. In the dirt in which they 

 buried themselves, however, I found a pupa evidently of some kind 

 of Tachina fly, but, as it did not produce the mature insect, the 

 species could not determined. These parasites seem to have ac- 

 complished the work of destruction much more thoroughly than 

 man possibly could have done ; for where last season these Span- 

 worms could have been counted by the thousands, the present sea- 

 son (1881) there was scarcely as many individuals. 



The Span-worms referred to above were, many years ago, named 

 "Lime-tree Span-worms," by Dr. Harris, from the supposition that 

 they preferred the lime-tree to all others ; but in this locality they 

 do not seem to have a preference for any particular tree or shrub, 

 and as they have become so injurious to the orchards, and so 



