3S8 C. II. TURNER 



backward, the fly will move in the same sense. By this means 

 Plateau succeeded in inducing a fly to move almost a meter 

 from its original position. This work of Plateau convinced 

 lYrex that it is not the beauty of the flowers that causes the 

 flies to hover before them. Perez soon noticed that the flies 

 hovering before the flowers were always males, and that the 

 darting sidewise was initiated by the arrival of small insects. 

 Suspecting that the male was lying in wait for a female, he 

 captured a female of the same species and released it near the 

 hovering male. At once the male darted after it. Although the 

 copulation was not observed, Perez thinks mating occurred. 

 According to Perez, Homalomyia manicata Meig., Homalomyia 

 la acalaris F., Anthomyia pluvialis L., and Anthomyia albicincta 

 Fall, engage in complex dances in which the flies rise and fall 

 in vertical planes. None but males participate in the dances. 

 When a female appears and a male succeeds in reaching her, 

 he abandons the dance. If a number of females are turned 

 lcose in the midst of a number of dancing males of H. mani- 

 culata, in a short while all of the dancers will disappear. Lim- 

 nibia chorea Meig. has a complicated dance in which the male 

 flies move in horizontal rather than vertical planes. Neither 

 Calliphora erythroccphala nor Lucilia caesar engages in dances. 

 In each of these species the male rests quietly on some support 

 until a female comes within range, and then darts after her. 

 In Chloria demandata Fabr. males and females walk about on 

 some isolated surface. When a male approaches a female, he 

 describes circles about her. After circling in one direction for 

 a short time, he turns about and moves in the opposite direc- 

 tion. After this has been repeated several times the flies mate. 

 These experiments caused Perez to conclude that both the 

 stationary hovering of the Syrphidae and the aerial dances of 

 other flies are means of securing mating. This seems to be the 

 most logical interpretation of this behavior that has been pro- 

 posed. The hovering of the Syrphidae in one place, the aerial 

 dances of certain flies, the posing of others on surfaces and the 

 sun -dances of certain bees are all brought under the head of 

 what has been termed a "nuptial ambuscade." * 



* C. H. Turner. The Sun-Dance of Mellissodes. Psyche, 1908, 122-124. 



