22 AJ^ A ceo UNT 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 Fulex, 

 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 

 " AVanderings." Although this is not a British insect, a short 

 description is appended, as its history is so extremely interesting. 



Metamorphosis of the Flea {Pidex). 

 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 



Fig. I. — Larva of/", felis (enlarged). — a, antennas ; 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. i). The last segment may have two strong, 

 curved hooks ; the head is sub-ovate and corneous. Antennae and 

 oral appendages are present ; also a pair of eyes. 



Although these worm-like larv^ 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 larvre, and there 

 disgorges some of its feast. This congealed blood is often found by 

 the larvae, 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. 



