^"^ AND ^"^^^^ 



JOURNAL OF VARIATION. 



Vol. VII. No. 4. November 15th, 1895. 



Cerura bicuspis in Herefordshire. 



By T. A. CHArMAN, M.D., F.E.S. 



This must always be one of our rarer moths ; at least, it is very un- 

 likely that large bags of it will ever be made, though it is quite possible 

 that it may be domesticated like A. alni. Tilgate Forest has, I believe, 

 at one time or other yielded large numbers by breeding or semi- 

 domestication, and the species seems to occur over almost the whole of 

 England. In Herefordshire it is now very rare, owing to the alder being 

 a gradually disappearing tree. My hunts after C. bicuspis have almost 

 always been after the pupai, and though this is a most unremunera- 

 tive search, it serves as an excuse for a winter constitutional when one 

 would not take one without some such real or imaginary object. 



The total proceeds in moths have been very small indeed, so 

 much so that both Dr. Wood's captures and mine have failed to com- 

 plete his series, all Herefordshire specimens, since Dr. Wood regards a 

 non-Herefordshire insect with the same kindly feeling that the average 

 lepidopterist bestows on a " continental specimen." Nevertheless one 

 meets with a large number of empty cocoons of various dates, and it is 

 from these that my knowledge of C. hicusjds as a Herefordshire insect is 

 chiefly derived. The rarity, even of the empty cocoons, has led me to 

 suppose that many larv* leave the tree altogether, and wander 

 off in search of pieces of rotten wood or other suitable positions, 

 wherein to pupate. 



A freshly-spun cocoon (I have seen very few) has a different tone 

 from the surrounding bark, and would, one would suppose, be easily 

 seen ; by midwinter, however, the tone differs very slightly, and after- 

 wards there is little or no difference between the cocoon and the sur- 

 rounding bark — the lichens, etc., which the larva raises to the surface 

 of the cocoon in spinning it probably growing a little in the damp 

 autumn weather. A cocoon a year or two old often strikes one as being 

 certainly invisible but for the hole in it, and frequently also from the 

 margin of the cocoon separating from the bark around, due to the 

 stretching of this by the growth of the tree. 



The emergence of the moth leaves a small opening at the upper 

 end of the cocoon ; when ichneumoned, the swarm of Chalcids (the 

 commonest enemy) emerges by a smaller hole nearer the middle of the 

 cocoon. More frequently than either of these, however, the cocoon has 

 a large part of the front missing, unquestionably the work of birds, 



