172 



BRITISH MOTHS. 



purple-brown, and sometimes absent ; the legs 

 and claspers are of the same colour as the body. 

 The MOTH appears on the wing in June and 

 July ; is one of our very commonest species, 

 occurring in every field, land, and hedgerow 

 throughout the summer. (The scientific name 

 is Camptogramma bilineata.} 



MALE. FEMALE. 



339. The Gem (Camptogramma jluviata}. 



339. THE GEM. The antennae are pecti- 

 nated in the male, the pectinations being very 

 short and inconspicuous. The male has the 

 fore wings clay-coloured, inclining to wains- 

 cot-brown, with a narrow transverse median 

 band of a smoky-brown, and including a 

 small black discoidal spot, which is surrounded 

 by a pale ring ; there is an oblique smoke- 

 coloured shade at the tip of the wing, descend- 

 ing towards its centre ; the clay-coloured area 

 on both sides of the median band is traversed 

 by faint white lines, the two more conspicuous 

 of which are between the band and the hind 

 margin ; the first of these is waved, the second 

 zigzag. The fore wings of the female are 

 purple-brown, sometimes inclining to brick- 

 dust-red ; the median band is faintly indicated, 

 but the discoidal spot is very conspicuous, 

 rendered so by the ring which surrounds it 

 being snowy-white : the hind wings in both 

 sexes are pale brownish gray, with waved lines 

 both lighter and darker : in each sex the head, 

 thorax, and body are much the same colour as 

 the fore wings. 



I have found the CATEBPILLAR of this 

 geometer on the leaves of the common persi- 

 caria (Polygonum persicaria), but I have not 

 described it from nature, as a very accurate 

 description which I have quoted below was 

 previously published in the " Entomologists' 

 Intelligencer" for 1858 : "A lovely female of 

 this species laid me some EGGS on the 24th of 

 July ; they were oblong, flattish, and yellow, 

 but changed to a dusky brown colour on the 



1st of August; the following day the CATEK- 

 riLLAKs hatched ; at first, they, were vcry 

 clingy, but on the 8th of August became dusky 

 sap-green, and on the 16th assumed their 

 characteristic markings. There were evidently 

 two distinct varieties, one of which had the 

 ground colour of a greenish gray, tinged with 

 red between the segments; the spiracularline 

 blackish and irregularly interrupted ; the back 

 (except the last two segments) dusky, having 

 on the intermediate segments a row of five 

 elongated diamonds of the ground colour, with 

 a dusky dot in each ; on the front segments 

 these markings ran into three parallel dusky 

 lines, while on the end segments there were 

 four slender dusky lines arranged in a diamond 

 pattern ; the claspers had a dusky stripe 

 running down them. The other variety had 

 the ground colour of a light yellowish green, 

 quite yellow between the segments ; the 

 spiracular line and pattern on the back faintly 

 indicated by dusky black lines and dots. 

 These caterpillars feed readily on groundsel 

 (Lenecio vulgar is\ at last eating through stems 

 bigger than themselves ; but, as their frass 

 seemed very watery, I doubt whether this is 

 their proper food. They were quiet in their 

 habits, resting on the under side of the leaves, 

 hiding themselves skilfully, and could not be 

 easily dislodged ; when disturbed, they curled 

 up the front segments, but not into such a 

 twisted knot as I have sometimes seen in more 

 slender geometers. From the 21st to the 

 23rd of August the caterpillars, being full- 

 fed, spun up in moss. Alter having been in 

 chrysalis about a fortnight, the perfect insects 

 emerged. There went down two of the green 

 and four of the darker caterpillars ; there have 

 come up again one C. Jluviata (male), and five 

 C. gemmaria (female) such a narrow risk did 

 I run of missing the solution of this problem. 

 Solved, however, it is, and C. Jluviata and C. 

 gemmaria are hereby declared to be man and 

 wife. I expected to find the difference of 

 colour in the caterpillar would turn out to be 

 a sexual one ; this, however, has been contra- 

 dicted by the result. The CHRYSALIS is brown, 

 smooth, spiked at the tail, and enclosed in a 

 thin silken cocoon iu moss. I have now seen, 



