244 . FLOWERS AND THEIR WORK. 



butterflies (especially red), while flowers visited by other 

 insects are usually white, yellow, or variegated; but there 

 are far too many exceptions to allow of a general rule. 



270. Butterfly- and Moth-Flowers. When the flower- 

 tube (or at any rate the level of the honey) is more than 

 about 12 mm. (about half an inch) deep, the honey is beyond 

 the reach of bees, though they may visit the flower for pollen 

 or the humble-bee may bite through the tube and thus rob 

 the flower of its honey. G-ood examples of butterfly-flowers 

 are seen in Red Campion and Bagged Robin, but butterflies 

 also visit many flowers adapted for bees, most British butter- 

 flies and moths having tongues of about the same length as, 

 or a little longer than, those of bees (about 15 mm.). 



Some moths, however, have far longer tongues (30 mm. in 

 a few British species), 1 which are (as in butterflies) carried 

 coiled up in a spiral under the head when flying. These 

 moths can reach honey even when it is at the bottom 

 of a very long tube, as in the Honeysuckle, which is 

 visited chiefly by the night-flying Privet Hawk-moth, and 

 the White Convolvulus, which is said to be pollinated by 

 another species of Hawk-moth (Sphinx convolvuli, tongue 

 80 mm. long), and to set seed very seldom in England owing 

 to the rarity of this moth. Other flowers pollinated by 

 night-flying moths are the White Campion (Lychnis vesper- 

 tina), Evening Primrose, Tobacco Plant, Privet, Bladder 

 Campion. Moth-pollinated flowers are white or pale-coloured, 

 sweetly scented, and open in the evening, usually remaining 

 closed and almost scentless during the day. 



Examine the following moth -pollinated flowers : Tobacco-plant, 

 Honeysuckle, Evening Campion, Evening Primrose. Make and 

 sketch a longitudinal section of each flower. Note the condition of 

 the flowers at different times (day and evening), and try to follow all 

 that happens in a single flower from the time it first opens until it 

 finally closes (after being pollinated). 



271. The Flower-Tube. It is interesting to compare the various 

 ways in which the flower becomes tubular in form, so as to protect the 

 ovary, to conceal the honey, to shelter the pollen from rain, to exclude 

 short-tongued insects, etc. The study of development shows that, 



1 In some foreign moths the proboscis reaches the astonishing length 

 of 3(30 mm. (about 12 inches). 



