172 INTRODUCTION 



unconsciously effecting its pollination, appears from the following observations of 

 Hermann MuUer (' Alpenblumen,' pp. 156, 339, 341, 362). At the summit of the 

 Albula Pass this observer saw a Macroglossa stellatarum visit several hundred flowers 

 of Primula integrifolia in the space of a few minutes. Another individual, in the 

 same short time, visited several hundred flowers of Gentiana verna, G. bavarica, and 

 Viola calcarata, as wefl as several blossoms of Gentiana excisa. Two more of these 

 moths visited, respectively, 106 flowers of Viola calcarata in barely four minutes, and 

 194 in 6f minutes. 



Diurnal Lepidoptera act quite diff'erently when visiting flowers. Hermann 

 Miiller (Kosmos, iii, p. 424) gives an exceedingly accurate and attractive picture of 

 the way in which butterflies behave. They pay their visits to flowers in an easy, 

 playful way, not like earnest workers for a living, but as if it were, next to love- 

 making, the most agreeable amusement in the warm sunshine. Flowers are their 

 public pleasure resorts, which ofler them in addition to the sweet pleasures of nectar, 

 the most favourable opportunity of exhibiting their gay clothing, and entering upon 

 affairs of love. But they are ready at any moment to forsake the blossoms, be it to 

 whirl through the air with the first good comrade that by chance appears, or to flutter 

 after a female, or to flee from an imaginary danger. 



According to Delpino (' Ult. oss.,' Atti Soc. ital. sc. nat., Milano, xvi, p. 345), 

 male butterflies (Pieris, Rhodocera, Limenitis, and others) pursue the females un- 

 ceasingly, so that they pass with great rapidity from the inflorescence of one plant 

 to that of another. This habit increases in very high degree the probability of 

 the cross-pollination of different stocks. 



Lepidoptera, especially the moths, possess an exceedingly keen sense of smell. 

 Delpino (op. cit.) relates that having left a female of Bombyx Pavonia major in 

 a small case at a half-open window, three males had joined the female on the 

 following morning, having apparently been attracted by her odour, although this 

 could not be perceived by Delpino himself Attention has already been called 

 (p. 125) to Kerner's experiment with Sphinx convolvuli, which proves the keen 

 sense of smell of this moth. 



Lepidoptera are hence very aptly termed the ' flowers of the air ' an expression 

 first used by Jean Paul (cf Kosmos, i, p. 260) not only on account of their 

 brilliant colour, but also in some cases because of their odour. According to Fritz 

 Miiller (Kosmos, iii, p. 187), the odour of the hind-wings of Papilio Grayi 

 (a native of South Brazil) is so strong and aromatic that this investigator carried 

 the insect about in his hand for the purpose of smelling it from time to time like 

 a flower. The male of another butterfly, Morpho Adonis, smells like vanilla (Fritz 

 Miiller, op. cit., p. 419), as do many lepidopterid flowers. 



The odoriferous organs which occur in many Lepidoptera (and rarely in other 

 insects) are only found in the males, the odours proceeding from which undoubtedly 

 attract and stimulate the females. These odours are exhaled from modified scales 

 known as androcom'a, which vary greatly in form, arrangement, and position. They 

 are generally situated on the wings, more rarely on the trunk or tibiae. Ethereal 

 oil passes up from cells lying at the bases of these scales, is distributed over them, 

 and then evaporates. The resultant odour can be clearly perceived on the fingers, 

 after wiping the dust from the wings of a living male Pieris napi or rapae. The 



