ECOLOGY OF FLOWERS: POLLINATION 



171 



wire netting which covers a piece of fresh meat or a dish of 

 syrup, and bees, wasps, and hornets will fairly besiege the 

 window screens of a kitchen where preserving is going on. 

 Many plants find it possible to attract as many insect visitors 

 as they need without giving off any scent, but small flowers, 

 like the mignonette, and night-blooming ones, like the white 

 tobacco and the evening primrose, are sweet-scented to at- 

 tract night-flying moths. It is interesting to observe that the 

 majority of the flowers which bloom at night are white, and 

 that they are much more generally sweet-scented than flowers 

 which bloom during the day. A few flowers are carrion- 

 scented (and purplish or brownish colored) and attract flies. 



203. Colors of Flowers. — Flowers which are of any 

 other color than green probably in most cases display their 

 colors to attract insects, or occasion- 

 ally birds. 



It is certain, however, that colors 

 are less important means of attrac- 

 tion than odors, from the fact that 

 insects are extremely near-sighted. 

 Butterflies and moths cannot see 

 distinctly at a distance of more than 

 about flve feet, bees and wasps at 

 more than two feet, and flies at more 

 than two and a fourth feet. Prob- 

 ably no insects can make out objects 

 clearly more than six feet away;^ 

 yet it is quite possible that their attention is attracted by- 

 colors at distances -greater than those mentioned.^ 



1 See Packard's Text-Booh of Entomology , p. 260. 



2 See Lubbock's Flowers, Fruits, and Leaves, Chapter I. On the general 

 subject of colors and odors in relation to insects, see Knuth-Davis' Handbook ' 

 of Flower Pollination, Clarendon Press, Oxford. 



Fig. 127. Stamens and 

 Pistil of the Grape (mag- 

 nified), with a Nectar 

 Gland, g, between Each 

 Pair of Stamens. 



