t»LEBfilUS ARGUS. 213 



venter grey-green. Head small, intensely black, shining. The large 

 compressed prothorax, with a conspicuous chocolate-brown patch in 

 centre. The body clothed with exceedingly fine short hairs ; those on 

 the dorsal area the longest, and curve backwards. Third moult (most 

 forward larvae) during first week in June. Fourth instar (full grown 

 June 20th): Length 12-5mm. at rest; 14mm. when extended; the 

 prothorax protuberant, flattened and rounded in front, completely 

 concealing the head ; from mesothorax to 6th abdominal (both 

 inclusive) the dorsum is considerably elevated, the segments of 

 uniform size, their sides flat and sloping to the lateral dilated ridge, 

 the mesothorax rising abruptly above the prothorax ; the last three 

 posterior segments are flattened, especially the anal segment, which 

 terminates in a broad, rounded, much compressed flap, similar to pro- 

 thorax ; the 8th abdominal is furnished with two retractile tubercles, 

 which are occasionally thrust out when the larva is alarmed, otherwise 

 they remain withdrawn, forming short blunt processes ; these structures 

 are pale straw-yellow in colour, and, surrounding the apex of sheath, is 

 a series of black warts, each terminating in a short spine resembling a 

 thorn. The ventral surface of the larva is much flattened, and, while 

 resting, it lies so flat that the true legs and prolegs are almost hidden. 

 Head very black and shining. Ground colour of body very pale green ; a 

 dark purplish mediodorsal stripe runs down its entire length ; broader 

 on prothorax, bordered on either side by a white line, then a pinkish and 

 green band blending into the pale green of the ground colour, followed 

 by a conspicuous subdorsal dark green stripe, composed of a series of 

 rather oblique marks, one on each segment, and a somewhat similar 

 stripe, but narrower, running parallel to it immediately above spiracles ; 

 a subspiracular, dark green stripe, edged below by a white stripe, passes 

 along lateral ridge which borders on the green of the ventral surface. 

 Spiracles white. The entire surface thickly sprinkled with black and 

 white granulations, the white ones predominating, each granule 

 emitting a very minute, fine, ochreous hair ; those along the dorsal 

 surface longest and stoutest. The true legs greenish ; the prolegs 

 green and brown-pink. The segmental incisions well-marked, the 

 segments strongly defined, and somewhat overlapping. [Another 

 form of larva, of almost equally frequent occurrence, has the first sub- 

 dorsal and subspiracular stripes lilac-red, with the ground-colour 

 usually more tinged with olive, giving the whole a decided reddish 

 hue (Frohawk).] 



Larva. — First instar (newly-hatched, Februarj^ 23rd, 1908): Grey- 

 brown in colour, semitransparent, with very dark hair-bases, those of 

 tubercle i so prominent, as to give the larva on side view a saw-edged 

 margin on top, not unlike Strymon pruni in its last stage ; the lateral 

 flange is also somewhat sharp and prominent ; the middle hair of the 

 three in the subspiracular (flange) set, is very long, and is a feature of 

 the larva on dorsal view. The head is black, and the dark prothoracic 

 and anal plates are easily seen. First instar (fullgrown, March 14th, 

 1908): As the larva grows in this stage, it becomes darker, and gradually 

 develops markings that are, at the end of the stadium, very pronounced 

 and distinct. The head is 0*25mm. across, black, polished ; the pro- 

 thoracic plate black, diamond-shaped, the prothorax as wide as 

 the 2nd abdominal, and the mesothorax nearly as wide again. 

 The larva is about 2mm. long, a fat, cylindrical, little fellow ; the pattern 



