THE PINE-BARK CHERMES : ITS SECRETION, ETC. l8l 



Similar secretions are produced by many other of the Aphididce. It 

 occurs in the sub-family of Apliidiiuf, in the beech aphis, Phyllajjhis 

 fagi (Linn.). In the Pemphiginoe we have many notable examples of 

 it, as in the woolly aphis of the apple-tree, iSc/uzoJieura lumgera (Haus.); 

 the woolly aphis of the elm, iS. tdmi Thomas; the woolly aphis of the 

 oak, S. querci Fitch; the alder blight, S. iessellata Fitch, etc. It also 

 pertains to many of the species of Pe»iphigus, and indeed, according 

 to Prof. Riley, is a feature common to the entire sub-family of Pemplii- 

 gince. 



From its occurrence upon so many species nourished by so greatly 

 differing food-plants, it is not strange that in appearance it should be 

 compared with such different substances as cotton, wool, silk, wax and 

 meal. Some of the material examined microscopically by Buckton was 

 found to consist of long flattened threads or fibres, with obscure, trans- 

 verse and longitudinal striations, and when broken to show strong 

 fractures as if they were brittle. That it was not of a waxy nature 

 appeared from its insolubility in alcohol and a solution of potash — its 

 scorching over a lamp without melting, and evolving a nitrogenous odor 

 like that of burned feathers. 



Of some of the species of Pemiihigus, Dr. Thomas asserts that they 

 do secrete a waxy substance that will melt under the heat of the hand. 



For remarks upon the secretions of some other Hemipterous insects, 

 pages 2S4-5 of my first report may be referred to. 



The Insect and its Changes. 



Within this secreted material, appearing as little downy balls fastened 

 to the twigs and branches, upon its being pulled apart early in the spring 

 the wingless mother of the pine-bark Chermes, may be found, together 

 with a number of her small yellowish, moderately ovate eggs — perhaps 

 from twenty-five to fifty. 



Early in April, in favorable seasons, the eggs commence to hatch. 

 The young larvae emerge from the ball and travel actively over the bark 

 for a short time. They are so small as to be almost invisible to the 

 naked eye, of an oval outline, flattened, of a light brown color, with 

 short legs, three-jointed antenna:, a sucking-tube extended beneath 

 their body, and a short hair on each side of the abdominal segments. 

 The two left-hand figures show the larva as seen from above and 

 from beneath. 



In the fore part of May, the larva: are more abundant than at any 

 other time. Their traveling soon ceases, and they attach themselves by 

 their beaks to the tender bark of the young twigs. As their feeding 

 proceeds, they increase rapidly in size, assuming a dark reddish-brown 



