36 
The caterpillar is greenish, with three yellow longitudinal lines, 
one along the back, the others on the sides; between these are several 
tubercular black spots, each bearing a pale hair; the tail is black; 
when full grown it is about an inch and a half long. The chrysalis is 
greenish gray spotted with black, with some yellowish stripes. In 
England this species appears about the middle or first of May, and 
about the end of the month deposits its eggs in clusters usually on 
the underside of cabbage leaves. The caterpillers soon hatch and 
continue to feed together till about the end of June. This summer 
brood remains in the pupa state, as a general rule, about sixteen days. 
Mr. Stephens, from whom I chiefly take these statements, remarks 
that during one season, when the species was very abundant the pu¬ 
pation of one brood was completed in seven days. 
P. Napi, Linn. 
As Mr. Strecker has introduced this species into the North Ameri¬ 
can list I give a description of it and also of some of its European 
varieties, which were for a time supposed to be distinct, as a means 
of comparison. 
Wings above, white, with the tip of the anterior dusky; the male 
with a black spot between the middle and hinder margin of the an¬ 
terior wings, the under surface of these wings has the nervures dusky, 
with the tips pale yellow, and two dusky spots towards the hinder 
margin; the posterior wings beneath, are pale sulphur yellow, with the 
nervures much dialated and dusky g*reenish; the nervures on the cos¬ 
tal edge of the discoidal cell with a clear yellow dash. The female 
has the anterior wings more rounded than the male, with two large 
black spots placed transversely and an obscure claviform dash towards 
the thinner edge; both sexes have a black costal spot on the posterior 
wings above; the body black with its under part white; the antennae 
white, annulated with black. 
Var. a —with the base of all the wings in both sexes deep black. 
Var. b —Male with the anterior wings immaculate above, with one 
indistinct spot beneath; the base of all the wings above, clear 
black. 
Var. c —Both sexes with the nervures of the posterior wings dilated 
at the base beneath. 
Var. d —Female with the wings yellowish above. 
Var. e —Dilated nervures of the posterior wings beneath, dusky in 
both sexes. 
The caterpillar is greenish-brown, clearer on the sides, with the stig¬ 
mata yellowdsh; it is covered with white tubercles with black tips 
bearing very delicate hairs. It feeds on the Brassica napus and 
similar plants, like its congeners. The chrysalis is greenish-yellow, 
spotted on the head and back; with the anterior edge of the wing- 
cases strongly spined. 
Var. A r apce —Like its congeners, this species varies considerably; the 
male has the upper surface of the wings milk-white, with the tip, a 
spot, and two or three triangular dashes on the hinder margin of the 
anterior, black; beneath, the latter have slightly dilated greenish nervures, 
with two cinereous spots placed transversely, and a yellowish tip; the 
posterior wings are pale yellowish with a deeper costal streak; the 
