THE BLACK ARCHES. I05 



the most northern, and, as adverted to, it has now become a 

 pest in parts of North America. 



The Black Arches {L^mtm^t4^ monacha). ^ ^^c/^^"*^ 



Two examples of each sex of this moth are figured on *>. ^" 

 Plate 46, and these show the normal form of the species ; the ^^i<^ ^ 

 central markings of the fore wings vary in width and intensity, *^^5^y 

 and in some specimens the whole of the central area is more or ^ /v 

 less filled up with black or sooty black. Sometimes the wings ^_^ 

 are partially suffused with blackish, and the normal markings 

 are consecjuently somewhat obscured. Examples wholly suffused 

 with black are referable to var. ere mi fa, a form not un- 

 common on the continent, and modifications of it are found in 

 a wild state in this country. By selecting parents showing a 

 tendency to vary in the direction of this dark form, it has been 

 found possible to obtain a good percentage of darkened speci- 

 mens, some of them closely approximating to var. eremifa. 



The early stages are figured on Plate 47. 



The eggs of this species are laid in August in the chinks of 

 bark on tree trunks, and do not hatch until the spring. 



Caterpillar, whitish varying to greyish, a deep brown stripe 

 along the middle of the back with an irregular black line on 

 each side of it ; the stripe is interrupted by a whitish or greyish 

 patch on rings seven to nine ; on ring two there is a black 

 mark, and occasionally red dots appear on eight and nine ; 

 black dots on the back and sides are furnished with hairs. 

 Head, brownish marked with a paler tint. It feeds from April 

 to July on the leaves of oak and various other trees, including 

 apple and pine. 



The chrysalis, which is enclosed in a somewhat transparent 

 silken cocoon spun up in a fissure of the bark, is lirownish, 

 hairy, and has a very glossy metallic appearance. 



The moth emerges at the end of July and in August. It Hies 



