NO. 7 PROTECTIVE ADAPTATIONS McATEE 87 



From the foregoing table it is evident that crane flies (Tipitlidae), 

 midges (Chironoinidae) and mosquitos (Culicidae) are adequately 

 represented, and it is fair to say that an important reason for this 

 showing is that the groups of birds eating most of these flies and their 

 larvae have been examined rather recently and that in consequence 

 closer identification of their food items has been made. This would 

 indicate that records for the other families will be similarly increased 

 by future studies. It is worth noting that most of the larvae of 

 Chironomidae which are so commonly eaten by birds are red (a 

 warning color) so much so as to be popularly called " bloodworms." 

 There are numerous instances of hundreds of these larvae being taken 

 at a single meal. 



The more than 10,000 records of Diptera mark these insects as a 

 valuable bird food ; as in other cases certain birds prey to a greater 

 extent upon the group than others ; of these may be cited seven species 

 of swallows which make 13 per cent to 40 per cent of their total food 

 of flies and an equal number of flycatchers consuming them to the 

 extent of from 11 per cent to 44 per cent of their entire subsistence. 



Total number of identifications, 10,836 ; percentage of identifica- 

 tions among those of all insects, 5.6757; percentage of species in this 

 order among the whole number of insect species known, 11.4432. 



Other enemies. — Fishes are among the most important enemies of 

 flies having aquatic immature stages. Pearse, writing of the food of 

 33 species of fishes in Wisconsin lakes, reports 20 per cent of their 

 food to consist of flies and their larvae, chiefly the latter. Marine 

 Chironomidae are eaten by shrimps and sea-anemones. A variety of 

 fishes, the top minnows and killifish in particular, are such efficient 

 enemies of mosquito larvae that they have been widely used in 

 mosquito-control campaigns. Diptera are eaten quite freely by frogs 

 and toads and to a lesser extent by lizards, snakes, and turtles. Among 

 mammals, shrews, moles, and bats feed regularly and extensively upon 

 Diptera ; other mammals that get at least some Diptera are mice, 

 squirrels, foxes, and armadillos. 



Among their own kind, i. c, insects, about all the predacious kinds 

 feed freely on flies. The latter are soft-bodied insects easily pierced 

 by the sucking predators or chewed up by the biting kinds. Tiger 

 beetles, assassin bugs, mantids, ants, panorpids, dragonflies, and robber 

 flies and other predacious members of their own order habitually feed 

 upon flies. ;\ number of families of wasps, such as the Nyssonidae, 

 Bembecidae, Crabronidae, and Vespidae, prey freely upon Diptera, 

 and spiders gain from their ranks a considerable share of their sub- 



