SYRPHIDAE OF MAINE. 199 



its success not to the hardiness or resistance of the individuals 

 but to their remarkable fecundity, for the individual aphid is 

 conspicuously frail, defenseless and exposed throughout its 

 life. 



Because of this frailty aphids are attacked by large numbers 

 of predators and parasites. The best known of the groups of 

 aphid enemies are: (i) the parasitic Hymenoptera; (2) the 

 Ladybird Beetles or Coccinellidae ; (3) the Lace-winged Flies, 

 Aphis-lions or Chrysopidae ; and (4) the Flower-flies or Syrph- 

 idae. The parasitic Hymenoptera complete their transforma- 

 tions from eggs to minute wasps inside the body of a single 

 aphid. The latter three groups are predaceous and grow, not 

 at the expense of a single aphid, but by catching and eating 

 dozens or hundreds of them. The Coccinellidae have achieved 

 a good deal of popular interest so that there is hardly a school 

 boy but knows that the Lady-birds eat plant-lice and are the 

 farmers* friends. The Syrphidae, on the other hand, seem to 

 be little known and much misunderstood by the farmer. This 

 deplorable lack of a better popular knowledge of this group 

 is a little hard to explain. Perhaps the principal reason is that 

 they have been so little discussed in entomological and popular 

 literature ; and the lack of a good common name may have 

 had its influence. Although it gives little or no intimation 

 of the economic importance of the group, and may even be 

 misinterpreted as indicating a habit injurious to flowers, the 

 name "Flower-flies" seems to be the most satisfactory of the 

 names in use;, because it is based on the most characteristic 

 habit which is uniformly true for the adults of the family: 

 viz, that of visiting flowers for the purpose of getting food. 



As contrasted with the Lady-birds, the movements of the 

 Syrphid larvae are slow, their colors subdued and their general 

 appearance quite inconspicuous, even repulsive. Their elon- 

 gate flattened bodies are often nearly or quite covered from 

 view by the aphids or their secretions. They are consequently 

 usually overlooked or ignored ; or the adults persecuted as 

 "sweat-bees," under the wholly erroneous idea that they can 

 sting; or, worse still, the flies may be accused of being respon- 

 sible for the presence of the lice on the plants, or the larvae 

 for the damage resulting from the plant-lice. 



