The _male Orange-Tip_ needs no description, for the purpose of recognition, beyond that conveyed by his name; but as the _female_ is less known, and has been on several occasions mistaken for the rare Bath White (_Daplidice_), it will be well to point out her chief distinguishing characters. The difference between the two insects certainly is obvious enough, when the two are _seen_ together, but their written descriptions read rather alike. { 92}
The female _Cardamines_ has the wings white _above_, with a greyish black tip, and a _small oval_, or _crescent-shaped black spot_ (much smaller than that of Daplidice) near the _centre_ of the front wings; _beneath_, a white ground, with green marblings, that are much more sharply defined than those in _Daplidice_. Near the centre of the front wing is a _clear black spot_, corresponding in position with that on the upper surface, _and not shaded off with green, as in Daplidice_.
We speak of the _green_ marblings of this species--and, to the naked eye, they do appear to be of quite a bright green--but under a microscope or powerful lens that colour disappears, being resolved into a combination of bright yellow and pure black scales, which, with the dazzling snow-white ground scales that surround them, form a microscopic tableau of extraordinary beauty. This can, however, only be seen by daylight, for under artificial light the yellow, on which the whole effect depends, is entirely lost.
The _caterpillar_ is slightly hairy, and green, with a white stripe on each side. It has been generally stated that the _Cardamine impatiens_ is the common food plant of this species, _apropos_ of which I will quote the following communication from Mr. Doubleday to the editor of the _Zoologist_:--
"In reply to your query about the food of the larva of _Cardamines_, I may say that I have found it upon several plants. I believe that _Cardamine pratensis_ (common cuckoo-flower) is the one on which the eggs { 93} 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_."