I08 FLEAS, FLUKES AND CUCKOOS 



are small, compact, and rather dumpy, whereas the Ceratophyllidac are 

 elongated, loosely built fleas. 



All the characters mentioned here, besides of course many others, 

 can be picked out on the labelled photograph. 



The British Bird Fleas* 



THE COMMON HOUSE-MARTIN FLEA, Ceratophyllus hiruudinis; farren's 

 HOUSE-MARTIN FLEA, C. farreui; the scarce house-martin flea, 

 C. rusticus; the Scottish house-martin flea, Orneacus rothschildi (Plates 

 XIII-XVII and Map i). All the first three species are found pullu- 

 lating in the nests of house-martins. The fourth, the Scottish house- 

 martin flea, is very rare and has only been found once — in Scotland. 

 Nine specimens were revealed among 4,000 C. farreni, thus showing 

 that it is well worth while examining all the fleas present in a single 

 nest. 



The first reference to a British bird flea concerns one of these species. 

 Hill (1752) remarked that "fleas are not confined to man and quad- 

 rupeds but are also found in swallows' nests." However, he shared 

 Linnaeus' view that they were all one species. Long after it was known 

 that mammals harbour different sorts of fleas, it was still thought that 

 all bird fleas were one and the same " Pulex avium", until Dale's 

 unfortunate decision to name every flea from a new bird host 

 as a diflerent species greatly increased the confusion. 



C. hirundinis is described as the commonest and most widespread of 

 the British house-martin fleas, C.farreni as a fairly common species, and 

 C. rusticus as rare. The two former species have both been recorded in 

 several thousands from single nests, but until quite recently (see 

 below) C. rusticus has only been found in small numbers. The ecology 

 of these fleas is extremely interesting but the study of it has so far been 

 entirely neglected. All three species have been found in the same nest, 

 in the same locality, in the same season and apparently all occupy the 

 same ecological niche. They would, therefore, appear to come into 

 direct competition with one another. This is of course^a most unlikely 



♦Since the completion of this manuscript Allan (1950) has found a further species 

 in the nest of the house-martin in Scotland, Frontopsylla laetus, a bird flea with an 

 alpine-boreal type of distribution. He also collected a further series of Orneacus 

 rothschildi from the same nest. 



