142 OBRURA BIFIDA. 



on 8, and then contracts, either touches the spiracle or 

 encloses it on 9, then slopes up and becomes narrow 

 on 12, widening out again on 13 ; the colouring, as in 

 furcula, is very rich ; the dorsal mark brownish with a 

 lilac bloom on it (growing mealy lilac as the larva 

 approaches maturity) ; there are traces of a thin, pale 

 dorsal line through it ; on segment 8, and sometimes 

 on 7, 8, and 9, it contains on either side some orange 

 or yellow blotches irregularly triangular with the 

 broad end in front, sometimes also there are other and 

 smaller yellow spots on these segments, the saddle- 

 mark edged first with red or purplish-red, and then 

 more broadly with yellow; the sides and belly rich 

 green, set above with some small yellow dots, and 

 below with yellow-bordered red dots, the spiracles 

 brownish-red and enclosed in small reddish spots ; on 

 3 or 4 are faint yellow false spiracles ; the face 

 brownish, with the top of the lobes black, the mouth 

 lilac, the neck pinkish, the rough spots on front of 2 

 brown, thoracic legs greenish with red joints, the 

 ventral prolegs with a small yellow-bordered red 

 streak, and a red half-moon above the foot, a double 

 purple ventral line on 12 and 13, wider on 11, and 

 joining the streaks on the prolegs of 10 ; the tails 

 roughish, green above, lilac below, with yellow rings, 

 the whips when protruded seem purplish ; the red 

 dots on the sides bear little bristles ; at the tip of the 

 anal flap are two sharp points, and another pair under- 

 neath, which are used to throw the pellets of frass to 

 a distance. 



The larva makes its cocoon on the bark of the 

 poplar tree, a yard or so from the ground, gnawing 

 out a hollow, and mixing the gnawed bark with silk. 

 I have several cocoons, some cut from trees, others 

 made on touchwood ; they vary in length from 25 mm. 

 to 30 mm., and in breadth from 8 mm. to 12 mm; 

 those on bark are adapted in shape as well as colour 

 to their surroundings ; one on touchwood is beauti- 

 fully oval and regular in outline ; the most curious is 



