142 FERTILIZATION OF SPRING FLOWERS ON THE YORKSHIRE COAST. 



share of the mid-tongued flies ; Class A B, with the honey half-hid 

 from the visiting insects, attracted more of the mid-tongued flies, 

 and a less percentage of short-tongued flies; Class B attracting 

 more than its share of long-tongued flies, less of short-tongued 

 Diptera, makes a thii-d to this series, which here suddenly is 

 broken by the great numbers of MuscidaB and Scatophagida) 

 visiting Class B'. Of the other classes, H and F are neglected 

 by the flies to whom the honey is quite unattainable. Of W and 

 Po in the scarcity of facts it is unsafe to speak. The long-tongued 

 bees are noticed to be individually scarce on the Composites, while 

 on Classes B and A they are fairly numerous. The small per- 

 centages for the bees on Classes H and F are due to the immense 

 numbers of Thrips thronging these flowers. The mid- and short- 

 tongued bees are specially numerous on Class AB. 



Table IV. 



—Percentage-Distribution of Insects visiting 

 THE various Classes of Flowers. 



At a season when G4-5 per cent, of the flower-visiting insects 

 are short-tongued flies, it would seem that the most successful 

 species should be the flowers fertilized by them. Perhaps it is so, 

 and Tussilcif/o, Bellis, and Taraxacum may be dominant on that 

 account. 



In Table V. the dominant species of the period under investi- 

 gation have the proportions of the insects abroad and flower- 

 visiting assigned to them. Some explanations are necessar}'. In 

 '95 the long cold winter caused the vegetation to be about a week later 

 than that of '96, when the winter had been extremely mild. There- 

 fore the weeks {see Table I.) do not correspond, but that lettered C 

 (Mch. 80 to Apr. 5, '95) corresponds to c. (Mch. 23 to 29, '96) ; 

 similarly D. and d. correspond. In Table V. these have been added 

 together. When a species was at the height of its flowering period, 

 the percentages of the visiting insects seen on it are in heavy type ; 

 when only commencing or ceasing to flower, the figures are in italics. 

 Thus it is seen that Tussiiaf/o began to flower before observations were 

 commenced, reached its best in weeks B, C, and D, and after this 

 diminished. At first 83'2 per cent, of the insects abroad visited it, 

 then Bellis began to compete seriously, then Salix, and then when 

 Tussilatjo had nearly ceased 'Taraxacum came forward. These 

 species all were abundantly visited by flies (as will be shown in 



