The Dance-Flies and the Long-Legged Flies 



dropped the balloon upon the ground and it was greedily seized 

 by ants." It seems probable that this observation by Professor 

 Aldrich will explain all of the cases in which dance-flies are seen 

 to carry such structures. 



Many of the species do not capture their prey by flight, but 

 run rapidly about on the ground catching other insects with their 

 front legs. The female, as in certain other predatory groups 

 which we have mentioned or will mention, resents the approaches 

 of the male, and if he be incautious seizes him and dispatches him 

 at once. The only time at which he can with safety make his 

 advances is when she is busy eating some other insect. 



The larvae of the dance-flies are cylindrical, and live in the 

 earth under leaves and in decaying vegetation. They are said to 

 be probably carnivorous. One species was reared, however, 

 from human faeces in the course of certain investigations made by 

 the writer on the subject of the flies which may carry the germs 

 of tpyhoid fever, but of course they may have been preying upon 

 other insects which were feeding in this substance. The pupae 

 are said to be free and to possess two points at the front end. 



The Dolichopodid flies are rather small and rather slender 

 species, usually greenish or bluish in color and more or less 

 metallic. Their wings are clear, or they may be dusky or ob- 

 scurely banded. They possess long legs, from which fact they 

 are called by Comstock "the long-legged flies," which, however, 

 does not seem to be a good popular term, since there are other 

 flies with much longer legs. Just as with the dance-flies, these 

 creatures are predatory and capture small flies of other groups, 

 and even soft-bodied worms. They are found in damp places 

 upon the leaves of aquatic plants, and some of them are able to 

 run rapidly over the water. The proboscis is short and not as 

 strong as with the robber-flies. It is a large group, and about 

 twelve hundred species are known. Many forms occur in this 

 country. With none of the species, however, has a good full 

 life history been studied out. The larvae live in the earth or in 

 decaying vegetable matter; some are found under the bark of 

 trees or in flowing sap. They form a cocoon and the pupa has 

 two long breathing tubes on the back of the thorax. 



T4'5 



