AMORPHA POPULI. 483 



protective in A. populi and in M. tiliae have either degenerated 

 from coloured borders or are on the way to become such, but that it 

 seems unlikely that the character can have a different significance 

 in the two species. She considers that spot marking is the more 

 ancestral, and that M. tiliae represents a stage of its modification 

 into stripes, etc., but the material on which the observations were 

 made was too small for safe generalisation. 



Pupation and cocoon. — The larva usually prepares for and 

 undergoes its pupation quite on the surface of the soil. Hellins 

 says that home-bred larvae burrowed an inch or two into loose 

 soil, but that, when pupa-digging, the pupa is found barely hidden, 

 and there seems to be scarcely any silk used in spinning. Bacot 

 says the larva never appears to spin any silk, nor is the pupa 

 enclosed in a cell, although an abundance of material be supplied; 

 as a rule, the larva burrows only just beneath the surface and 

 then pupates. The larva generally burrows, but comes to the 

 surface again before pupating, however much earth be given it 

 (Arbuthnott) ; of more than 50 pupae dug at High Wycombe be- 

 tween 1892-1899, only two were found under willow, all the rest 

 under poplar (Peachell) ; pupae at Oxton, mostly at roots of elm 

 (Studd) ; pupae dug at roots of poplar, also at roots of elm where 

 no poplar trees existed (Russell); in the ground about ioin. deep (!) 

 (Lambillion) ; pupa taken at the roots of species of poplar, May 

 27th, 1901, at Burnley (Clutten) ; larva buried October 24th, 

 1886, cocoon just below surface, slightly exposed, and did not pupate 

 until November 23rd, i.e., in 4 weeks and 2 days, although I have often 

 turned pupae out in half this time ; pupae dug commonly, October — 

 April, under willows at Clapton, under poplars at Stamford Hill; on 

 August i5th-i6th, 1887, at Clapton, under aspen (James); pupae under 

 willow and Lombardy poplar (Eddrup) ; the larvae pupate in the 

 ground, and are sometimes found at the roots of lime trees (Clark) ; 

 rather common at foot of poplar (Hollands) ; common in Septem- 

 ber and October, 1859 and i860, at roots of poplar (Fenn) ; 

 frequently dug at roots of Lombardy poplar in Gloucester and 

 Surrey from September — Febuary (Prideaux). 



Pupa. — Length 33mm. — 36mm., width 10mm. {$) to 13mm. 

 ( ? ) ; these are average rather than extreme dimensions. Colour : 

 black, with a suspicion that it is rather an extreme of brown than 

 an actual black, intersegmental membrane brownish. The general 

 structure is Amorphid, i.e., ordinary obtect, with labrum ventral, 

 and glazed eye with convexity forwards. The form is less cylindrical 

 than in the other species, i.e., it is more decidedly thicker at the 4th 

 abdominal segment, tapering to either end. Thus, the diameters of a 

 specimen are, at mesothorax 10mm., at the 2nd abdominal segment 

 1 imm., at the 4th segment 12mm.. at the 5th segment 1 imm., and at the 

 6th segment 10mm. Except some dorsal depression on either side of 

 the metathorax and 1st abdominal segment, which affects also the 

 wings adjacent, forming a "waist," the transverse section would 

 everywhere be very nearly circular. The curvature anteriorly is, 

 however, almost entirely dorsal, the front of appendages being 

 nearly straight. From labrum down vent er^ [the lengths are — to 

 end of maxillae 6 # 5mm., to end of first legs 9'5mm., of antenna 

 iomm., of second legs u^mm., to end of wings 15mm., the costae 



