Dragon-Flies 



ones are undoubtedly captured by the legs, and are consumed 

 during flight, and so rapidly is all this done that it is practically 

 impossible to see the operation. The only way, in fact, that one 

 can know that an insect has been captured is, as Dr. Needham 

 expresses it, to see that the place that once knew them knows 

 them no more. 



Flies seem to be their commonest food, but large dragon-flies 

 will eat small ones. Leaf-hoppers and even small butterflies and 

 moths are captured by them. Some forms will occasionally pick 

 up a moth from a weed or a grass stem on which it is resting, 

 and even one of the large swallow-tailed butterflies has been seen 

 captured by a dragon-fly, while Williamson states that he once 

 saw one holding a large wasp in its jaws. The voracity of a 

 large dragon-fly may easily be tested by capturing one and hold- 

 ing it by its wings folded together over its back, and then feed- 

 ing it live house-flies. I should hesitate to say how many it will 

 accept and devour, as I never tried one to the limit of its capacity. 

 Beutenmiiller found that one of the large ones would eat forty 

 house-flies inside of two hours, while a smaller one ate twenty- 

 five in the same time. It is an odd fact that a dragon-fly will 

 eat its own body when offered to him. Even when insufficiently 

 chloroformed and pinned, if one revives, it will cease all efforts 

 to escape if fed with house-flies, the satisfying of its appetite 

 making it apparently oblivious to the discomfort or possible pain 

 of a big pin through its thorax. There is one record to the effect 

 that a dragon-fly has been observed feeding upon the flesh of a 

 dead reptile. 



Although dragon-flies are frequently very abundant in 

 swampy regions and about ponds, there are times when they 

 swarm in enormous numbers. Koppen, a German entomologist, 

 has published a chronological account of the records of dragon- 

 fly migrations, from 1494 to 1868, Such migrating swarms 

 seem to have been more frequently noticed in Europe than in 

 this country, but several have been noticed in the United States. 

 For example, Mr. A. H. Mundt, of Fairbury, Illinois, says that 

 between the hours of 5 and 7 P. M., August 13, 1881, "the 

 air for miles around seemed literally alive with these dragon-flies 

 (/Eschna heros) from a foot above ground to as far as the eye 

 could reach, all flying in the same direction, a southwesterly 

 course, and the few that would occasionally cross the track of 



365 



