MIMICRY OF HYMENOPTERAN ANTENNAE 
BY SYRPHIDAE* 
By G. P. Waldbauer 
Department of Entomology 
University of Illinois 
Many flies of the Family Syrphidae mimic aculeate Hymenoptera. 
The hymenopterans, particularly vespid wasps, which serve as models 
for these syrphids have relatively long, many segmented, filiform an- 
tennae which are often in motion and are usually a conspicuous 
feature. Most syrphids, like all of the other cyclorrhaphous Diptera, 
have three-segmented antennae which are usually short and decidedly 
inconspicuous as, for example, are those of the non-mimetic Tropidia 
quadrata (Say) (fig. i). To human eyes the absence of conspicuous 
antennae decreases the resemblance of mimic to model, and the effect 
is presumably the same to at least some of the species of predators 
which are to varying degrees deceived by the mimetic resemblance. 
I have observed in nature several species of wasp-mimicking syrphids 
which either have or give the appearance of having long, filiform 
antennae. In each case the living mimic is remarkably deceptive and 
only close observation reveals that wasp-like antennae are not actually 
present. 
The antennae of Sphecomyia vittata (Wiedemann) (fig. 2) and 
Ceriana signifera (Loew) (fig. 3) have been lengthened. The first 
and second segments of the antennae of S. vittata are very long while 
the third is short and bears an arista. The apparent length of the 
antennae is further increased by the forward-extending process of 
the head capsule which bears them. In C. signifera the first and 
third segments are quite long while the second is of only moderate 
length. The third segment bears a terminal style rather than an 
arista, further extending its length. In life both species hold the 
antennae in positions which suggest the geniculate antennae of vespids. 
The antennae of Tenthredomyia abbreviata (Loew) (fig. 4) ap- 
pear to be long because they are borne by a long, forward-extending 
process of the head capsule. The antennae themselves have been but 
slightly lengthened. The first segment is moderately long, but the 
second and third are short although the third bears a terminal style 
rather than an arista. As in the preceding two species living specimens 
of T. abbreviata hold the antennae in such a. way that they appear 
* Manuscript received by the editor January 19, 1970. 
45 
