TRICHIURA CRATAEGI. 489 



Williams notes that a batch spread its hatching from April 3rd, 1891, 

 to the end of the month. Milliere notes the eggs as hatching in 

 the autumn in Cannes, and this seems to be the general habit of the 

 moorland var. ariae. 



Ovum. — The egg forms a flattened oval, inclining to rectangular in 

 outline ; the length, 15 micro-millimetres ; breadth, 10 micro-millimetres ; 

 height, 5 micro-millimetres ; with a large shallow depression occupying the 

 greater part of the upper surface ; the micropylar end is a little squarer 

 than its nadir, the latter being perhaps a little broader. The shell is 

 of a dark chestnut-brown colour, shining, and is seen to be exceedingly 

 finely pitted, and longitudinally striated under a high power. The 

 micropylar area occupies the whole of one end, the micropyle proper 

 being placed centrally in a slight depression at this. The embryo does 

 not develop until late in the winter (Bacot failed to find any trace of it 

 in an egg opened on January 18th, 1896). The whole of the micro- 

 pylar end is eaten out circularly when the larva makes its escape ; but 

 there is no colour change in the egg-shell before hatching owing to its 

 opacity. Crewe describes the egg as of a rich chestnut colour, paler 

 at the base, which is flattened. When looked at through a glass, he 

 says, it reminds one much "of a ripe acorn." We fail to see the 

 similarity. The simile is, however, repeated by Barrett. 



Habits of larva. — We have already noted that the var. ariae 

 lays eggs that batch in the autumn, that the young larvae hybernate the 

 first winter, feed up and pupate the following summer, some emergences 

 taking place in autumn, other pupae going over the winter and not 

 producing imagines till the following summer (an exactly parallel life- 

 history to that of Lasiocampa quercus var. callunae). Milliere strangely 

 notes a similar habit of autumn-hatching larvae along the Biviera, 

 where one would scarcely expect it, and where the need of a long larval 

 life is less evident than in the high altitudes and latitudes that var. 

 ariae inhabits. Generally in central Europe the eggs are laid in autumn, 

 do not hatch until spring, the larvae become full-fed in June, remain as 

 pupae until September, when the imagines emerge. The young larvae 

 when newly emerged spin a slight web over a part of the food-plant, 

 and are gregarious for a time. In their second stadium they rest in small 

 groups, and appear to prefer a twig with no smaller twigs branching 

 from it. They cover such parts of it as they rest upon with silk, and 

 though they leave it to obtain food they return again to rest on the same 

 twig. They love to bask in the morning sun, and towards the end of May 

 and beginning of June, when they have separated, and also later when they 

 are almost full-fed, they may usually be found sunning themselves on the 

 small blackthorn or whitethorn bushes, stretched out lengthwise on a 

 twig, on the outskirts of woods and thickets. Holland notes that it is 

 an irregular feeding species — only the quickest feeding ones appear to 

 be successful, some batches feeding on slowly through most of the 

 summer and then almost always die in the last instar. This appears to 

 be a remnant of the moorland habit, which is unsuitable to the low- 

 lying districts, and which natural selection, perhaps, does its best to 

 eliminate, although one might suppose that the necessity for rapidly 

 coming to maturity in its southern localities would be of little 

 moment to a species with such diverse larval habits as this. 

 Williams notes the larvae as feeding by preference on closely-cut haw- 

 thorn hedges and loving the sun. Merrin observes that in the Bristol 



