36 OHIO BIOLOGICAL SURVEY 



ficed in the acquiring of this experience. If any badge comes to stand gen- 

 erally for an unpleasant experience, the species possessing it will be left 

 unmolested, and so, to some extent, will be other forms though lacking 

 in the unpleasant or distasteful quality, if they possess the same sort of 

 markings. This will be true only so long as the distasteful form exceeds 

 in individuals met with, the harmless form; and the greater the 

 preponderance of mimicked individuals the better the protection of the 

 mimicker. 



Now it seems to us that the one badge, which, to the human eye at 

 least, suggests the unpleasantness of a sting, is the black and yellow ab- 

 dominal markings mentioned above. Is this not also true of the preda- 

 ceous enemies of >S)v^///V/^(?' ;** If so, we have perhaps an explanation, or 

 rather a utilitarian justification, for the existence of these resemblances. 



It should be stated that this resemblance in color, pattern, and form 

 is given significance by the similarity in habit of many of the two groups. 

 Both are to be found buzzing or hovering about flowers, especially in the 

 sunlight, or crawling in and out of the blossoms. The casual observer 

 never distinguishes many of the Syrphidae from the numerous and varied 

 Hymenoptera always to be found about melliferous blossoms. 



Of course the most striking structural difference between these two 

 groups is the presence of four wings in the bees, and only two in the flies. 

 The structure of the mouth-parts is also very different. But these are by 

 no means the most ready ways of distinguishing the two in the field. 

 The Syjphidac have a distinctive manner of flying which has given them 

 the name of "Hover-flies." They constantly poise or hover in the warm 

 sunlight like a hummingbird. They remain suspended in the same 

 position for a longer time than a bee, apparently without moving their 

 body at.fill, and with wings beating so rapidly as to be practically invisible. 

 Or the}^ dart away suddenly, seeming to keep the body always in a tense 

 horizontal position. In the case of a bee there is habitually more or less 

 weaving back and forth of the body and bobbing up and down. 



This is one of the ready means of distinguishing these insects in the 

 field. Again the long, elbowed antennae of a bee are comparatively 

 conspicuous when it is in flight; while, of course, the short ones of the 

 great majority of the Syrphidae are not visible at a little distance. 

 Another thing worth noticing is that when at rest on flower or leaf, 

 the Syrpln'd W\\\ frequently keep its wings half spread, read>- for flight; 

 while those of the bee are closelj' folded or crossed over at the tips. 



A few of the best cases of protective mimicry might be mentioned. 

 That of the drone-fly, or chrysanthemum fly, Eristalis teriax, is known 



