THE STATE ENTOMOLOGIST. 46 



The moth expands about 0.45 inch and has the front wings of a deep 

 glossy purplish-gray, marked with two transverse pale bands, as in the 

 figure (d). It may be popularly known as Hammond's " Knot-horn." I 

 first received specimens of this worm in the summer of 1869, from Mr. A. 

 C. Hammond of Warsaw, and W. T. Xelson of Wilmington, Ills. My 

 late associate, Mr. Walsh, had intended to describe the species, and I now 

 carry out his intention by naming it in honor of Mr. Hammond, whose 

 experience with it, as given in the following extracts from one of his letters, 

 will throw further light on its habits : 



In August and September, 1868, I noticed that the leaves of my apple 

 trees were being destroyed by some insect. An examination revealed the 

 fact that the mischief was caused by a small greenish larva about half an 

 inch long, with two dark stripes on its back. Their mode of operating 

 appearecl to be to locate themselves on or near the end of the twigs in commu- 

 nities of from three or four to a dozen, and form a dwelling place by 

 webbing together a quantity of leaves with a material resembling spider's 

 web. Within this shelter they live, feeding upon the leaves. 



In June, 1869, I found the same insect at work in my orchard in great 

 numbers. At this time the apples were about one-fourth grown, ancl we 

 found that the worms generally inclosed two or three apples within the mass of 

 leaves and that they were feeding upon these as well as upon the leaves, of 

 course causing them to drop. Their ravages wei^e principally confined to 

 a few varieties. The yellow Bellflower, Winesap and Ben Davis ajjpeared 

 to be their favorites. They had caused fully one-half of the fruit to fall 

 fi'om several hundred trees in my orchard. 



In Europe a larger species of a closely allied genus (Acrohasis consoci- 

 elld), which I have received from Mr. P. C. Zeller of Pi'ussia, works upon 

 the leaves of the oak in very much the same manner as ours does on those 

 of the Apple ; and it is one of those insects attended by a companion larva, 

 Our insect seems to be similarly attended by two companion larvae, namely, 

 the two sj^ecies next to be treated of. At least it is almost always found in 

 conjunction with them. So far as we now know there is but one annual brood 

 of the Apple-leaf Skeletonizer; but the moths issue very irregularly, and 

 the worms may be found all through the summer, but particularly in the 

 fall, as long as the leaves remain on the tree. I have found but partially 

 grown worms as late as JSTovembcr — unfortunates that seemed doomed to a 

 wintry death. The moths commence to make their appearance in the vicin- 

 ity of St. Louis by the first of May, but I have had them issue as late as the 

 last of Jul}^. 



Eemedies. — This insect, like a good many others, shows a decided pre- 

 dilection for unthrifty, tender trees, and careful, clean culture is the best 

 preventive. A little hand picking at the proper time will do much to 

 prevent its injuries, and I incline to believe that it may be extirpated by dust- 

 ing the trees with air-slacked lime. I have bred from it two small Ichneu- 

 mon-flies, one of which is a Microgaster ; but during my absence last 

 summer the specimens were destroyed b}^ mice. The larva of some Lace- 

 wing fly (CArysopa) also preys upon it, and its round white cocoon may often 

 be found among the skeletonized leaves, and should be saved. 



