22° AN ACCOUNT OF BRITISH FLIES. 
live only upon vertebrate blood, but recent discoveries show this to 
be a fallacy. They are found in large colonies in dry sandy places, 
where they could not attack vertebrate animals. To make up for this 
they make for caterpillars and other invertebrata, and suck their 
juices. There are a good many species, each animal seeming to 
have a particular one to itself. They may attain a great size, such as 
Pulex gigas, from America; but our species never attain any great 
dimensions. By far the greater number belong to the genus Pw/ex, 
but one that has attracted considerable interest forms another genus, 
Sarcopsylla. This genus contains the curious and obnoxious “ Jigger” 
of South America and Africa, so well described by Waterton in his 
‘‘ Wanderings.” Although this is not a British insect, a short 
description is appended, as its history is so extremely interesting. 
Metamorphosis of the Flea (Pulex). 
Each female lays about a dozen eggs at a time. The eggs are 
oblong, or spindle-shaped, and generally whitish in colour. They 
may be, however, brown in some species. The ova are deposited in 
Fic, 1.—Larva of P. felis (enlarged).—a, antennz ; P, pointe frontale. 
various places, such as the cracks in boards, amongst dust, on the 
hairs of rugs and dogs, and various other places, according to the 
species. 
After a time these eggs hatch, and from them come worm-like 
maggots, very active. The larva is composed of thirteen segments, 
and is quite apodous (Fig. 1). The last segment may have two strong, 
curved hooks; the head is sub-ovate and corneous. Antenne and 
oral appendages are present ; also a pair of eyes. 
Although these worm-like larve are active, they never move far, 
and their mode of nutrition has been disputed and discussed a great 
deal. It seems true that the female, or mother, after having gorged 
itself upon the blood of its victim, makes off to its larva, and there 
disgorges some of its feast. This congealed blood is often found by 
the larve, and upon it they feed. It is also said that they gain 
nourishment from the fleshy part of feathers, etc., which may happen 
to be close to them. 
