LIFE HISTORIES OF FAMILIAR PLANTS 



the end of May, and it is a sunny afternoon with 

 little or no wind. As we reach the tree we observe 

 that the air round about it is swarming with flies ; 

 moreover, from the grass and hedges near at hand 

 swarms of flies of many and varied species rise, as 

 we move, buzzing upwards. Why these flies are 

 gathered there becomes obvious presently ; they 

 are seeking the sycamore flowers. There are 

 blow-flies, flesh-flies, dung-flies, house-flies, hover- 

 flies, alder-flies and innumerable other species ; 

 there are honey-bees, humble-bees, and solitary bees 

 of many kinds ; indeed it is a veritable flies' picnic. 

 We pull down by means of our walking-stick 

 one of the hanging racemes of flowers, and at 

 once become aware of its strong honey-like scent, 

 and at the same time we perceive that the flowers 

 are quite sticky by the abundance of a sugary 

 substance that they are producing. Why the 

 sycamore entertains this motley throng of insects 

 we have now to see. 



In the first place the sycamore's flowers have 

 no showy petals to attract bees, butterflies, and 

 moths ; bees are attracted in large numbers, but 

 by the strong, sweet smell of the nectar. In truth 

 the sycamore lays out its flowers especially for 

 pollination by flies ; its yellowish and brownish 

 green flowers are a kind of fly speciality, attracting 

 them much more strongly than would brightly 

 coloured flowers. In Fig. 15 (Plate 11) are shown 

 some fully-developed examples of the flowers, and 

 a wild bee is seen travelling along one of the leaf 

 stalks. Also in the top left-hand comer is seen 

 • 24 



