MIMICRY 
531 
Simon’s Town, S. Africa, October 3, 1905. I had much difficulty in 
distinguishing during life some flies—? Ploas sp., and Prorachthes 
sp.—from certain small black, white-ringed Bees, Halictus 
albofasciatus , Smith, <£, which buried themselves in the flowers 
of a large Mesembryanthemum ; in the cabinet the insects look 
distinct enough, but during life the resemblance, especially in 
their movements and habits, was quite remarkable (see p. 250, 
supra). 
Matheran, W. Ghats, 1908. At the end of March, in a time of 
extreme drought, insects of various orders were, naturally enough, 
attracted to such pools as were left about the nearly exhausted 
springs. Among the visitors were many long-waisted Wasps of 
which I secured a fair number, belonging, as I supposed on a 
cursory glance, to several species. When Mr. A. H. Hamm had 
set these for me at Oxford, he remarked, “ I see that you have 
taken a lot of Conops along with the wasps that they mimic.” 
Critical examination revealed:— Hymenoptera : Eumenes flavo- 
picta, Blanch., three; E. edwardsii , Sauss., one; Icaria fer - 
ruginea, Fabr., four; Polistes marginalis , Fabr., var. stigma, 
Fabr., one. Diptera : Ceria, sp. nov. (near trinotata, de Meijere), 
three; Ceria eumenoides , Saunders, seven. How close was the 
mimicry of Fly to Wasp may be judged from the figures on 
Plate IY. The mimicry of Icaria by C. eumenoides had been 
noticed by Col. C. G. Nurse in 1899, also at Matheran. 1 
Mortehoe, Devon, August, 1908. Two specimens of the common 
British fly, Conops flavipes, Linn., suggested to me when alive a 
Trochilium (Clear-wing Moth) rather than a Wasp. But the 
next one that I came across was netted on the wing as a small 
wasp. Subsequently other specimens were seen running about 
on leaves (especially of Hydrangea ), and the close resemblance 
of their moments to those of a Yespid were noticed on at least 
two occasions. The abdomen was frequently raised and de¬ 
pressed, and there was a general fidgetiness of manner that was 
highly suggestive of a wasp, but, unlike a wasp, the antennae 
remained rigidly porrected, so as to be strangely conspicuous. 
Mortehoe, Devon, 1906, and subsequently. The Syrphid fly, Chilosia 
illustrata , Harr., which is to be seen commonly enough on 
Ragwort flowers and various Umbellifers, is a fairly close mimic 
of Bornbus sylvarum, Linn., and the more local Podalirius 
furcatus , Panz. They may often be seen side by side on the 
same flower-head, and it requires a little care to distinguish them, 
1 See above, p. 392. 
