THE FAUNA OF BIRDS NESTS 25I 



is far more closely linked with this habitat than the previous species. 

 The commonest moth in swallows' and martins' nests in England is 

 Hofmannophila pseudospretella and it has also been bred by Basden from 

 nests of the barn-owl, wren and starling. The larvae are scavengers and 

 will feed on faeces, dead nestlings and even addled eggs. Two other 

 moths, Monopis rusticella and M. ferruginella, are also commonly associ- 

 ated with nests of many birds in this country. There are, however, in 

 Britain, no true symbiotic moths comparable with the species usually 

 present in the nest of the Australian golden-shouldered parrakeet [Psepho- 

 tus chrysopterygius) . The larva of this moth lives unobtrusively in the 

 bottom of the nest, and, hke a well-trained nurse-maid, not only tidies 

 up the nursery, but with meticulous care cleans the droppings off the 

 nether limbs of the nestlings. 



Chief among the scavengers are the fly larvae. As we have seen in 

 Chapter 12, some of these have become true ecto-parasites on the 

 nesthngs and some facultative parasites, but there remains a fair number, 

 such as species of Fannia, Anthomyia, Hydrotaea and Phaonia, which, as a 

 rule, feed on refuse in the nest, although at times they may be semi- 

 predacious. A few species also parasitise other dipterous larvae. 

 Occasionally the magnificent metallic corpse-feeder Cynomyia mortuorum 

 is found in nests, and probably the larvae are not above suspicion 

 as facultative parasites. True parasites of nestlings are the larvae 

 Protocalliphora and Neottiophilum^ which are dealt with in Chapter 

 II (p. 221). Camus and Meoneura are thought to be ectopara- 

 sitic as adults, but their larvae probably live as scavengers in the 

 nest. There are also some groups of flies, Phoridae, Helomyzidae and 

 others, which occur quite frequently and are vegetable refuse eaters, but 

 are also found in carrion, dung and fungi. There are also a few 

 Hymenoptera which parasitise the larvae of fleas, flies and moths, and 

 are no doubt extremely useful to the birds. 



Generally each bird or group of birds has a characteristic nidicolous 

 fauna, in which certain species are found more frequently than others 

 or in larger numbers. In martins' nests in Britain, fleas are the 

 dominant and most important group (see p. 80). They are present 

 in over 80 per cent., and their numbers are greater and their species 

 more varied in these than in other birds' nests. Flies are the next 

 most important group, followed by moths. Here, however, there is 

 a divergence between the fauna of the ground nesting sand-martin 

 and the house-martin and swallow. Moths are an important group in 



