128 TURNIP. 



at full growth, and tapering slightly to each extremity. The colour 

 is variable, usually of a delicate or apple green ; but in younger state 

 the caterpillars are often yellowish or greyish, with black head. When 

 near full growth the head is usually grey or yellowish, and marked 

 with small black dots ; the next segment is remarkable for the absence 

 of the two dark patches often found in the case of small caterpillars 

 of allied kinds, and instead has a number of very minute black specks. 

 The rest of the segments have a few black dots. Each of the first 

 three segments bears a pair of claw-feet, and there are also four pairs 

 of sucker-feet beneath the body, and another pair (which are very 

 noticeable from being set out somewhat obliquely) at the extremity of 

 the tail. 



When full-fed, which may be in about four weeks, the caterpillars 

 spin their cocoons for the most part at their customary feeding-place, 

 the under side of the leafage of their food-plants, or on stems, &c., near. 

 These cocoons are sometimes a mere open net- work of white threads, 

 through which the colouring of the chrysalis can be distinctly seen ; 

 and, so far as I can judge from the many specimens which passed 

 through my hands in 1891 (the year of the great attack), there is a 

 good deal of variety in this matter. The characteristic colour when 

 mature is whitish with some black streaks ; in the early part of their 

 formation the cbrysalids may be green or brownish, and sometimes 

 the cocoons, instead of being a mere open net-work of white threads, 

 are thicker, and of a somewhat boat-shaped form. 



The moths may come out in from about one to three weeks from 

 commencement of the chrysalis state, and are of the size given at 

 "3," p. 127. The front wings are long and narrow, greyish brown 

 along the centre, and fore edge, with some small brown spots in front ; 

 a rather broad whitish or ochreous grey band runs along the hinder 

 margin, so shaped along its fore edge that when the moth is at rest, 

 with the wings laid along the back and their edges meeting, the pale 

 patterns form a row of diamond-shaped markings, whence the name of 

 Diamond-back Moth (see figures 4 and 5, magnified, p. 127). 



There may certainly be two broods during summer or autumn, and 

 the chrysalids from the latest brood of the year remain in this state 

 through the winter. 



Eeturning to the special point of sea gulls, and also of the kinds 

 of sea gulls noticed on infested land, it was in 1894 that Mr. W. D. 

 Anderson, whose note I give at p. 127, preceding, favoured me with 

 the following observation regarding their presence at the same locality, 

 namely, Ardsheal, Ballachulish, Argyleshire, N.B., during the month 

 of August. Mr. Anderson remarked : — 



"My attention was first drawn to the field where the caterpillar 

 was discovered by a large flock of gulls (herring gull, common gull, 



