LIFE-HISTOKY OF NYSSIA LAPPONARIA. 239 



black lines composed of numerous black specks and streaks, have 

 the inter-space of a leaden-drab colour, these bands being divided 

 by primrose-j^ellow lines, thus forming longitudinal rows of 

 alternating stripes ; the leaden-drab stripes are medio-dorsal, 

 sub-dorsal, super-spiracular. and spiracular ; on the latter band 

 are situated the spiracles, which are small and intensely black ; 

 each is placed on a squarish dull deep black spot forming a con- 

 spicuous row of spots, each is bordered on the lateral and posterior 

 sides with bright lemon-yellow, the yellow being again relieved 

 laterally by a black streak ; on the posterior half of each segment 

 uniting the medio- and sub-dorsal bands is a short transverse 

 lemon-yellow bar united to a black spot in the sub-dorsal band ; 

 the remaining details are in every way similar to the previous 

 stage. It rests in a straight position upon the stems of birch, 

 frequently straight along the stem, but sometimes only with its 

 claspers grasping it, and the head a short distance away, but 

 always with a silken thread from its mouth to the stem. The 

 fourth and last moult took place on June 18th. 



Figs. 6, 6 a. — After fourth moult, forty-two days old, and 

 fully grown, it measures 1| in. in length ; in every detail the pre- 

 ceding description agrees precisely with this stage, excepting that 

 the yellow markings are now rather deeper, of a gamboge-yellow, 

 and the ground colour of the dorsal surface is also rather deeper, 

 and of course the size increased when fully grown. The ground 

 colour varies in different specimens ; of the four larvae in my 

 possession three having the yellow of different depths, and the 

 fourth of a decided lilac-drab hue ; this, with the black markings, 

 assumed quite a deep drab-brown, closely resembling the colour 

 of the birch-stems.* The first larva buried for pupation on 

 June 27th, remaining in the larval state forty-two days. 



Fig. 7. — The pupa is ^ in. in length ; the head and thorax 

 uniformly rounded in front ; round the middle of the wings it is 

 rather contracted ; the fifth abdominal segment, including the 

 apical portion of the wings, is swollen ; the remainder of the 

 abdomen being attenuated ; the posterior segment terminating 

 in a slightly curved conical point cleft at the end ; on the same 

 segment at either side is also a short point ; the entire surface is 

 finely granulated ; the head, thorax, and abdomen of a deep red- 

 brown ; the wings, antennae, and legs are light sienna-red ; the 

 eyes are rather conspicuous and blackish. It has no cocoon, being 

 simply buried an inch or two under the surface of the earth. 



The following descriptions are taken from a pair of specimens 

 kindly lent me by Mr. Christy : — 



* Mr. Christy, referring to this colour variation in a letter recently re- 

 ceived from him, says: "The ground colour varies considerably; I have had 

 them dark purplish-brown so that they matched the birch-twigs, and I have 

 had them almost putty-coloured." 



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