affecting Carrots and Parsnips. 
18J 
The female butterfly will lay her eggs indiscriminately upon 
the leaves and flowers of carrots, the marsh milk-parsley (Seli- 
ntim pahistre), rue or fennel, the end of May and in June. The 
caterpillars of various sizes and colours may be found feeding in 
June and July; and the butterfly is sometimes seen until the 
middle of August. 
The caterpillars are black when first hatched, which colour 
they retain until they are half grown, being then ornamented with 
spots and rings of green, with warts producing minute brushes of 
bristles : when arrived at maturity they are nearly two inches long 
and as thick as a swan's quill ; they are then beautiful objects, 
being quite smooth, of a charming green colour, with black velvety 
rings, upon which are orange warts, excepting the alternate rings, 
which form a junction with the segments, and are often concealed 
when at rest. They have 6 black pectoral legs like horny claws, 
8 fleshy abdominal feet, and 2 similar anal ones for holding firmly; 
but the most curious distinction in the structure is a forked appara- 
tus, like a T, of an orange colour, inserted behind the horny head, 
w hich the animal can thrust out or withdraw at pleasure ; and 
this organ, which secretes an acrid fluid of an offensive scent, is 
believed to drive away the Ichneumons and other parasitic enemies, 
which would otherwise annihilate such a conspicuous species. It 
is generally in July that the transformation to the chrysalis takes 
place, when the caterpillar fastens its tail, spins a thread across 
its back, shoots off its skin, and assumes a yellow or green tint, 
with an interrupted black stripe on each side. 
The butterfly is the largest and finest species produced in this 
country, belonging to the Ordkr Lepiuopteka, the Family 
Papilionid^e, the Genus Papilio,* and it was named by Lin- 
naeus, 
4. Papilio Machaon, and is called the Swallow-tailed But- 
terfly, from the two appendages which emanate from the hinder 
wings. It is yellow with black horns : the head, trunk, and body 
are black, the sides striped with yellow : the upper wings have a 
large black space at the base freckled with }ellow, the hinder 
margin is black with a line of yellow crescents ; the nervures 
form black stripes, and there are 3 largish black patches above 
the disc : the lower wings have a broad black border with yellow 
crescents along the margin, and there are 6 freckled blue patches 
upon the back, with a brick-red eye-like spot at the anal angle, 
and a blue crescent above, the whole enclosed in a black ring ; 
the tails are black with a yellow edge inside : the wings expand 
from 3 to 3^ inches. 
* Curtis's ' Brit. Ent.,' fol. and pi. 578, where another species is figured, 
called P. Podaliriits, which seems to have deserted our island. 
