40 



ECOLOGY 



among the rcckli.sh-\cl]o\v or maroon 

 colored liairs that form a fringe near the 

 apex of the labellum. While in this po- 

 sition, peculiar movements of the in- 

 sect's body take place; the pollinia of the 

 orchid are dislodged and are affixed to 

 the insect's head. After the usual hv- 

 grometric behavior of the pollinia the 

 pollen masses are in a position for com- 

 ing in contact with the stigmas of the 

 next flower visited. Pouyanne observed 

 the action of the insect after the tip 

 of the abdomen had been inserted 

 among the hairs of the labellum and 

 described it as follows: "Le bout de 

 I'abdomen est alors agite, contre ces 

 poils, de mouvements desordonn^s, 

 presque convulsifs, et I'insecte tout 

 cntier se tremousse; ses mouvements, 

 son attitude paraissent tout a fait 

 semblables a eeux des insectes qui 

 pratiquent des tentatives de copula- 

 tion." 



Seeking to explain the behavior of 

 the males of Scolia ciliata, Pouvanne 

 conducted a series of experiments that 

 might prove enlightening. He cut off 

 the labellum of some of the flowers, 

 leaving the sepals, petals and column 

 intact. Flowers so mutilated were neg- 

 lected; the insects became quite indif- 

 ferent to them. If single flowers were 

 taken from a raceme and placed on the 

 ground, they were immediately ap- 

 proached. But when the separate 

 flowers were inverted with only the 

 under side of the labellum exposed, the 

 insects still came to them, yet with 

 lessened interest. If a bouquet of 

 flowers was held in the hand, the males 

 of Scolia ciliata came to it in numbers, 

 contending with each other for the 

 possession of a labellum. If, however, 

 such a bouquet was forced on the atten- 

 tion of the females, they exhibited in- 

 difference, and if pressed too insistently 

 flew away as if from something repug- 

 nant to them. If flowering specimens of 

 the orchid were concealed under sheets 

 of newspaper and thus hidden from 



view, the males of Scolia would ap- 

 proach, as if tr)'ing to reach the con- 

 cealed flowers, attracted, it would seem, 

 by some odor too faint for perception bv 

 human nostrils, because Ophrys specu- 

 lum is described as being without scent. 

 Pouvanne refers to the metallic, violet- 

 blue patch of color on the labellum of 

 Ophrys speculum as resembling the 

 metallic blue of the female of Scolia 

 ciliata when, at such times as the insect 

 is at rest or crawling on the ground, 

 the wings are half crossed. It is then 

 that the insect, if the sun is shining, 

 exhibits a metallic lustre, an irides- 

 cence, similar to that of the labellum of 

 Ophrys speculum. Even though the re- 

 semblance between the female of 

 Scolia ciliata and the labellum of the 

 orchid is hardly of a nature to deceive 

 our eyes, Pouyanne reminds us that the 

 vision of insects is myopic and less keen 

 than ours and that, moreover, in addi- 

 tion to even a faint resemblance that 

 might not in itself deceive the males of 

 Scolia ciliata, there is some subtle scent 

 that completes the deception and in- 

 duces the sexual phenomena he has so 

 convincingly described. 



From Pouyanne's experiments and 

 from the behavior of the insects there 

 was every reason to believe that Ophrys 

 speculum and the males of Scolia 

 ciliata are biologically adjusted for pur- 

 poses mutually advantageous, although 

 if the purposes are purelv sexual, as is 

 evident, then the orchid alone seems to 

 be biologically benefited bv the associa- 

 tion and, according to human stand- 

 ards, the insect seems to be sadlv hood- 

 winked. 



We may wonder how the brief time 

 between the emerging of the males and 

 the females of Scolia ciliata, about 

 thirty days each vear, was turned by 

 the plant through the ages to such ad- 

 vantage to itself, because in seasons 

 when the orchids are late in flowering 

 or the females of Scolia ciliata emerge 

 from their burrows earlier than usual. 



