536 BRITISH LEPIDOPTERA. 



in March and April. A batch in our possession hatched on May 12th, 

 1896, but there is great difference in this respect. 



Ovum. — The eggs are so pressed on each other and embedded in 

 stiff gum that the shape is somewhat obscured. Each egg appears to 

 be of the typical Lachneid form, the micropylar end placed outwards, 

 the nadir towards the culm or stem round which the batch appears to 

 be laid. It is flattened, and has a very large and distinct depression 

 occupying about two -thirds of what is really the upper surface. It 

 forms a rough oval in longitudinal section, with both ends broadly 

 rounded but rather wider at the micropylar end. The egg is whitish 

 in colour, opaque, shiny (with a varnished appearance), shaded with 

 dark sepia longitudinally, the eggshell being covered with minute 

 roughened points. The micropylar end of the egg consists of a raised 

 white convex surface, sculptured with an undefined labyrinth of very 

 slightly raised ridges and containing in its centre the true micropyle, a 

 minute, cone-like point, rising from a shallow depression composed of 

 very minute cells, placed quite centrally in the convex surface. 



Comparison of eggs of M. castrensis and M. neustria. — The egg 

 of M. castrensis is like a pulled fig in shape, 1-lmm. in length, -8mm. in 

 width, -6mm. in thickness, greyish- white in colour, darker where the 

 cement' is thicker ; it tapers from the micropylar end to the base, the 

 width and thickness at base being about "6mm. and *5mm. respectively. 

 The shell has an opaque porcellanus appearance, and under a 1" 

 objective a minute surface network may be distinguished. The egg of 

 M. neustria is very similar in shape, but with a tendency (not constant) 

 to have a raised micropylar area; it is l-2mm. in length, -7mm--8mm. 

 in width, and '6mm. in thickness. The eggs are so firmly cemented, 

 however, in this species that it is almost impossible to detach single 

 eggs without breaking them. The shell of the egg of M. neustria appears 

 to be double and much thicker than that of M. castrensis. The 

 micropylar area of 21. neustria is black, forming a noticeable dot in 

 the centre of the end at which it is placed. In the egg of 21. castrensis 

 the micropylar area is not coloured, but there is a slight dimple where 

 it occurs (Bacot). 



Habits of larva. — The eggs hatch in May, and the larvae are 

 gregarious until the penultimate moult ; but there is great difference 

 in the hatching period and the date at which the larvae are full-fed, 

 young larvae in their webs, and adult larvae, often being found on the 

 same ground at the same time. They feed in the web they make on 

 Statice Iwionium, Artemisia maritima, and other plants, but as the web 

 becomes larger they spread it to the short herbage on which they also 

 feed, and leave a trail (where they have eaten the plants) covered with 

 web. These may be found early in June on the mudflats of the Kent, 

 Suffolk, and Essex coasts, and are then some three or four inches wide 

 and one or two yards in length. The larvae themselves, although 

 brightly coloured, are not at all conspicuous at a little distance, and 

 are best found by following up one of their webs. Bacot says that a 

 nest made by the larvae when only a few days old is almost spherical, 

 an inch or less in diameter, the whole not unlike a nest of young 

 spiders in general appearance. The larvae are exceedingly easy to rear 

 on sallow and knot-grass, if kept in a well-ventilated frame, where 

 they can get full advantage of the sun, warmth and fresh air being 

 very essential to development. The larvae must have plenty of room 



