1970] 
Waldbauer — Mimicry 
47 
to be geniculate as are the antennae of the models. This orientation 
is retained even in some dried specimens. 
Spilomyia hamifera Loew (fig. 5) has antennae which are short 
and quite inconspicuous, similar in length and form to the antennae 
of non-mimetic Syrphidae (fig. 1). They are borne by a tubercle 
which is only slightly produced. In this case the long, dark, filiform 
antennae of the models are mimicked by the dark front legs which 
are held up and waved about in front of the head. The effect is 
very realistic and can easily deceive an inexperienced collector. The 
tarsi and the distal portion of the tibiae of the front legs are dark. 
The proximal portion of the front legs as well as the other two 
pairs of legs are yellow as are those of the models. I have observed 
this behavior in S. hamifera both while they were feeding on flowers 
or resting on foliage. Occasionally, all six legs are on the substrate, 
the usual position for most syrphids. I do not know in what position 
the legs are held in flight. 
I have observed a similar use of the front legs in three other 
vespid-mimicking Spilomyia , S. fusca Loew, S. longicornis Loew and 
S. quadrifasciata (Say). In each of these species the front tarsi and 
a part of the front tibiae are dark. The remaining legs are yellow 
except for dark areas on the femora of S. fusca and S. quadrifasciata. 
The legs of S. crandalli Curran and S. foxleei Vockeroth are similar 
to those of the last two species mentioned although the meso- and 
metatarsi of S. foxleei are somewhat darkened distally. S. kahli Snow 
does not have the front legs darkened. I have seen only pinned speci- 
mens of the last three species. It may be that S. kahli does not use 
the front legs to mimic antennae, but it seems more likely that models 
with yellow antennae will be found to occur within its range in the 
southwestern United States. Curran (1951) stated that all species 
of Spilomyia rest on the four posterior legs and use the front legs 
to mimic antennae. 
At least some of the North American species of T emnostoma use 
the front legs in the same manner. In nature I have seen this done 
by T. balyras Walker, T. pictulum Williston and T. trifasciatum 
Robertson. In each of these species the front legs are dark while the 
other two pairs are largely yellow. Although I have not seen them 
Figs. 1-5. Dorsal and lateral views of the heads of five species of 
Syrphidae. 
Fig. 1 . Tropidia quadrata (Say). Fig. 2. Sphecomyia vittata (Wiede- 
mann). Fig. 3. Ceriana signifera (Loew). Fig. 4. T enthredomyia abbre- 
viate a (Loew). Fig. 5. Spilomyia hamifera Loew. 
