are most frequently deposited, but the greater part of the larvæ must perish in this neighbourhood, because the fields are mowed before the larvæ are full-grown. I have very often seen the larvæ on the seed-pods of Erysimum Alliaria, and have several times found the pupæ on the dead stems of this plant in winter; I think that it is the principal food of Cardamines at Epping; it also probably feeds on E. barbarea, and other similar plants. Some years ago we used to have a quantity of a large single rocket in the garden, and there was always a number of the larvæ of Cardamines feeding on the seed-pods. Cardamine impatiens is so local a plant that it cannot be the common food of the larvæ of Cardamines."
The chrysalis is of the very singular shape shown at fig. 17, [Plate I]., a shape quite unique among British butterflies, though that of the next slightly approaches it. It is to be looked for in autumn and winter on the dry, dead stems of the plants named in the foregoing paragraph.
The perfect butterfly, which is very common throughout the country, is met with from the end of April to the end of May or beginning of June.
THE WOOD-WHITE BUTTERFLY. (Leucophasia Sinapis.)
([Plate V]. fig. 2.)
A glance at the figure of this graceful little butterfly (on [Plate V].) will suffice to distinguish it at once, and clearly, from all our other Whites. The most ordinary form of the insect is there represented, but there are specimens occasionally met with that have the blackish spot at the tip of the wings very much fainter; and sometimes, as in one that I possess, this spot is totally wanting. The shape of the wings in these is also different, being much rounder, and proportionately shorter, than in the ordinary shape. This difference in outline is, I believe, a sexual distinction, the more rounded form belonging to the female insect.
The slender, fragile wings and the attenuated body of the Wood-white give it a look of almost ghostly lightness, and its manners befit its spectral aspect, for it seems to haunt the still and lonely wood glades, flitting about slowly and restlessly, and being seldom seen to settle.
From its weak flight, it is a very easy insect to capture. It appears to be addicted to early rising, twenty-six specimens having been taken one morning before breakfast by a gentleman at Grange, in North Lancashire.