Syrphidae 409 



been found most convenient for feeding cages. The cage is held against 

 the host animal, the fly biting through the meshes of the wire. Flies re- 

 luctant to feed may do so if the muslin cap is removed from one end of 

 the cage and the open end set on the host. However, this procedure 

 greatly increases the hazard of losing the fly if the host becomes nervous. 

 The chances of success are much greater if the host is kept in full sun- 

 light during the feeding attempt. 



A few reared flies will feed in captivity and deposit eggs, but so far 

 as the writer's experience has gone, these eggs are never fertile. Mating 

 has never been observed by the writer either in cages or in the field. 



Reference 

 Family Phoridae 



For culture see pp. 401 and 402. 



Family 



SYRPHIDAE 



THE CULTURE OF APHIDOPHAGOUS SYRPHID FLIES* 



C. L. Fluke, Jr., University of Wisconsin 



THE culture of predacious syrphid flies has not been very successful, 

 although the securing of ova from the adults may be accomplished by 

 proper moisture, food, and lighting conditions. No substitute food for 

 the larvae has been developed. This statement refers to the forms prey- 

 ing upon aphids and other soft-bodied insects. 



The adults need water, which is best taken from a wick; light, such 

 as sunshine or light from an incandescent bulb; and a diet of dried yeast 

 50% mixed with sterilized honey 50%. The yeast should be dried, 

 sterilized, and pulverized before mixing with the honey. This forms a 

 thick paste which may be smeared near the top of screen cages. The 

 water wick should be placed near the top of the cage to take advantage 

 of the flies' habits of crawling and flying upwards. Small cages are 

 preferred to large ones and the plant leaves on which syrphid flies prefer 

 to lay their eggs should also be near the top of the cage. Moist sand 

 placed in the bottoms of the cages will maintain sufficient moisture for 

 the flies. 



Aphidophagous syrphid flies will lay eggs more readily on leaves in- 

 fested with plant lice than on uninfested leaves. Certain species are 

 apparently stimulated to lay when fed, in addition to the honey yeast 

 formula, a thin syrup of dextrose and levulose. 



The use of a sun ray lamp is not recommended as preliminary tests 

 have indicated that, while the adults appeared to be stimulated, all ova 

 secured at the time were sterile. 



*Unpublished results of a project sponsored by Wisconsin Alumni Research Foundation. 



