49 
grows tho larger, and perhaps feeds up a trifle the more rapidly ; my 
records for the larval period of jiligrammari-a range from about 98 to 
50 days. 
E. autamnata- with dilutata. I emphatically repeat that it is 
impossible to confound these in second, third, and fourth instar. In 
second instar, dilutata is of somewhat different build, much yellower- 
green, the head, prothoracie and anal plates less brown, &c.; in third 
and fourth it lacks the yellow longitudinal lines of autamnata, is often 
more or less marked with purple or brick-red, colours which never 
appear in that species, and still differs in shape ; indeed autamnata 
reminds me more in this respect of the genus Operophthera ( Cheima- 
tobia). In the fifth instar, on the other hand, the resemblance of the 
two becomes very striking, owing to the weakening off of the 
distinguishing longitudinal lines ; it is, however, only a small 
percentage of dilutata which continue devoid of purple or red markings 
up to this period, and it is of course only the unicolorous green forms 
which can be confused with autamnata. 
I take it that this approach of the adult larvre may be referable to 
their agreement in habit, both being tree-feeding forms, and requiring 
similar protection ; the more variegated aspect oi jilirjrammana up to 
the last is, I presume, no disadvantage to it on its low growing food- 
plants, but as I have never seen it in situ I cannot do more than 
speculate on this subject. While on the subject of habits, I may 
mention that my autamnata larva; were more restless under observation 
than jilvirammaria ; and this also I should attribute to the tree-feeding 
habits of the former, which would perhaps have a better chance 
of escaping by dropping or retreating on the approach of enemies, 
whil sfiligrammaria might reasonably trust more to rigid immobility. 
Food-plants. —Birch and fir (Doubleday, teste Guenee), larch (in 
Switzerland—Pungeler in lift.), alder (Enniskillen—J. E. R. Allen), 
oak (Greening, teste Gregson), birch, sallow, alder, aspen (Sp.-Schnei¬ 
der). My larvae were reared mainly on hawthorn, on which they throve 
well ; and they would probably eat the leaves of many other trees and 
shrubs. Nevertheless, there can be no doubt as to the predilection of 
the species for birch; Weaver, Logan, Gregson, &c., give this for 
Britain, Guenee for France (var. ;/ueneata ), Borkhausen for Germany, 
and various Scandinavian authors for Norway and Sweden. In 
Norway it is sometimes so extremely abundant that it is ranked 
among the injurious insects, occasionally defoliating the birch woods, 
in which case, pressed by hunger, it is found feeding on anything, 
even Aconitum (Wocke, Stett. Ent. Zeit., xxv., p. 189) ; and it is 
discussed at some length (under the name of dilutata) by Schoyen in 
the “ Norske Forstforenings Aarbog ” for 1891, and by Hagemann in 
his “ Yore Norske Forstinsekter ” in the same year; the larval 
descriptions and the material I have received from Prof. Aurivillius 
{vide, Ent. llec., ix., 249 ; x., 95) prove that it is the present species 
with which they are dealing. Mr. J. E. R. Allen had sent me some 
interesting notes from Enniskillen; the larvas which he obtained 
there last spring from hawthorn all without exception produced 
dilutata, while those from alder, only a few hundred yards away, all 
produced autamnata. He further noticed that a good percentage of the 
earlier dilutata larva; he obtained were marked with red or purple, but 
all the later ones were without it, >uid he failed fcQ distinguish them 
