AMERICAN HOMOPTERA. 367 



July 21st. — Tlie Bark-louse has grown much, has moulted again, 

 and its scale now presents three parts, distinct divisions, and conse- 

 quently is becoming thicker and stronger from day to day. Each new 

 skin cast and its cement are light ashen-grey, which together make an 

 addition to the scale at its posterior end, for by several such incre- 

 ments is the scale constructed, somewhat simulating shell growth in 

 Mollusca, but the upper older portion of the scale is reddish-brown. 

 The insects beneath are white, instead of yellow, as noted on the 7th, 

 evidently having just moulted; now, if the scale be turned up care- 

 fully with a fine instrument, the insect will be found attached by the 

 thread-like organ (proboscis) which arises out of a groove towards the 

 anterior extremity of its ventral surface ; this groove is formed by 

 two ridges, by this slender proboscis it holds on to the tree with great 

 tenacity ; if the scale is entirely removed the insect hangs fluttering in 

 the breeze. I have noticed a similar trembling or jerking motion of 

 the insect when protected from the wind, probably a muscular effort 

 expressive of dissatisfaction at the loss of its covering. When thus 

 exposed for a few days it invariably falls off and is lost; its house is, 

 therefore, necessary to its life. 



July 31st. — I now find the Bark-louse scale of nearly full size and 

 normal color ; the insect snugly enclosed ; the edges of the scale much 

 thickened and turn in under the body, firmly glued to the tree. The 

 insect no longer presents the jug-shaped form, but is oblong-ovate and 

 very suculent, and when crushed the eggs can be seen. 



Here and there, over the tree, I observe one out of about five hun- 

 dred scales, that present an abnormal form and color. They are pa- 

 pery-white, and much longer than the usual dark-colored scales, but I 

 am not able to discover any difference in the insect beneath the scales, 

 that is between this and those of the normal scales. 



Aug. 11th. — I observe that they are beginning to lay their eggs, 

 and from one to a dozen can be found under each scale, towards the pos- 

 terior extremity. The form of the insect is now oblong-ovoid, flattened, 

 cylindrical, instead of obovate, as observed during the progress of de- 

 velopment. The insect is attached by the same thread-like organ, 

 which is about as long as the body, and produces the same jerking mo- 

 tion after the scale is removed. It may now be seen, when the scale 

 is removed, by the naked eye at the distance of a yard or more, shak- 

 ing and jerking as if agitated by the wind. 



Auij. 17th. — I observe that the egg-laying season is progressing ra- 

 pidly ; most of the scales are filled with white eggs, posteriorly and 



