INTRODUCTIOK 
9 
attacliment by the four posterior pro-legs, at a very considerable angle 
to the twig on which it rests. This strange attitude, in association 
with special colouring and configuration, is eminently protective, render- 
ing the caterpillar almost indistinguishable from the twigs it frequents. 
Many caterpillars of Noduco, having in addition to two pairs of pro- 
legs possessed by the Geometers only one pair;(on the ninth segment), 
approximate the latter in their mode of progression, and are commonly 
known as " half-loopers." 
While nearly all lepidopterous larvee are solitary, or only found in 
close proximity owing to their having been hatched more or less re- 
cently from a cluster of eggs, there are a few among those of moths 
which are distinctly social, constructing a common silken nest in which 
they remain until eventually assuming the chrysalis state. The most re- 
markable of these social larvge are those of the so-called " Processionary " 
Bombycid moths, which not only live in community, but, when they leave 
the nest, proceed in long columns widening from the single leader to 
many abreast, and return, after feeding, in the same regular order.^ 
On its first disclosure by the moult of the last skin of the cater- 
pillar, the lepidopterous Puim or chrysalis exhibits a soft moist sur- 
face, usually of a greenish or yellowish tint, the viscid secretion upon 
which gradually hardens into a rather thin, but hard and firm, outer 
casing or horny shell, closely investing the entire body, and binding 
flatly upon the breast and sides the incipient trunk (haustellum), 
antennae, palpi, legs, and wings. It is very remarkable that in the 
chrysalis, from the very first, these various limbs are all distinctly 
present in outline, or in mould as it were, and are to a great extent 
free from the body at first, though subsequently the investing secretion 
glues them down. 
Pupae, leading an absolutely quiescent life and requiring no food, 
present but little variation in comparison to the larvge. In form, be- 
sides being more elongate and slender in some groups than in others, 
the only marked difierence is presented by the chrysalides of most 
butterfiies, in which the head and thorax are more or less sharply 
angulated. The surface in some is very smooth, but in most more or 
less granulated or pitted. Many of the angulated butterfly chrysalides 
bear on the back of the abdomen two rows of tubercles, usually more 
or less pointed, and in a few cases prolonged into spinous processes. 
Some of the Bombycid pup^ {Liparidm), and also that of a South- 
African Lyc^nid butterfly {U Urhania), have dense tufts of hair. 
The colours of pup« are considerably varied in the case of those 
fully exposed to the light or in very thin cocoons, but limited to various 
1 A characteristic "Processionary" inhabits the eastern part of Cape Colony and Natal ; 
it is the Anaphe Panda of Boisduval. 
Westwood long ago described a Mexican Pieride butterfly {EucJieira socialis), the larvse 
of which " construct a very strong parchment-like bag, in which they not only reside, but 
undergo their change to the pupa state ; " but he has not recorded, I believe, whether these 
caterpillars are processionary. 
