84- WHITE PINE LEAF-LOTJSE. 



two varieties ot" pine above mentioned. On the narrow leafet of 

 the White Pine, the scale — or I should specify, for reasons which 

 will appear hereafter — \h&fem,ale scale, has a slender and linear 

 form, exactly corresponding to the width of the leaf on which it is 

 moulded ; but on the broader leaf of the Scotch Pine, where it has 

 space to expand, it may be supposed to assume its normal shape, i 

 It here often appears almost in the form of an elongated triangle 

 with its terminal or shorter side rounded. Its generic tendency 

 to the muscle shape is perceptible only in one of the long sides 

 being nearly straight and the other a little more arched. 



Upon a more critical examination, these scales are seen to be 

 composed of three parts, one behind the other, gradually increas- 

 ing in size, and thus marking the successive stages of the insect's 

 growth. Mr. Walsh designated these parts, respectively, as the ' 

 larval scale, the medial scale, and the anal sack. The French 

 authors call the large terminal portion the buckler or shield, but 

 to avoid unnecessary changes I shall, in the present article, adopt 

 Mr. Walsh's names. Besides, the term anal sack expresses more 

 accnrately the composition of this part, it being turned under at 

 its edges so as to inclose the insect and its eggs. J3ut this inferior 

 lamina is very thin, and being adherent to the surface of the leaf 

 it is necessarily ruptured in raising the scale. 



The larval scale is of a pale, transparent amber color, and a 

 flattened, O'i^al form, slightly elevated or carinated along the mid- 

 dle, with transverse furrows on each side, indicating imperfectly 

 that division into rings or segments which characterizes all the 

 annnlose animals. The larval scale, as its name implies, is evi- 

 dently the moulted skin or envelope of the insect in its primitive 

 or larval state. In retreating from it, the insect leaves all its 

 members attached to it. 



The small, and scarcely more than rudimental legs, and the 

 slender anal lilaments become obliterated and indistinguishable 

 as soon as the larva is fixed ; but the antennae remain and can 

 generally be seen attached to the anterior extremity of the scale 

 after the lapse of a year, and after the insect beneath has passed 

 through all the phases of its existence. 



In leaving its larval envelope, the insect retreats a little upon 

 the leaf, and at the same time becomes clothed with a new integu- 

 ment, closely resembling the former, but a tint darker colored, 



