THE POLLINATION OF THE PRIMROSE 343 



effective substitutes for insects which are only of use in dry weather. 

 The evidence obtained regarding the visits of snails and slugs and 

 their behaviour in connection with Primrose flowers shows that it is 

 to some extent malacophilous. The Hemipteron (Drymus briinneus), 

 seen only on one occasion, must be classed as a casual and unusual 

 visitor. Mr. E. A. Butler, to whom I am indebted for the identifica- 

 tion, states that it would be an over- wintered example. 



The Sussex and North Wales observations, in conjunction, clearly 

 indicate that the flowers are visited by bees to a considerable extent. 

 Andrena Gwynana appears to be as important a visitor in North 

 Wales as Weiss has shown it to be in Shropshire ; here too it was 

 actively engaged in collecting pollen, as the nectar was of course out 

 of reach : this could readily accomplish pollination, especially in the 

 long-styled flowers. As might be expected, at this season the insects 

 in evidence were mainly queens. Six examples which were captured 

 were queens, but one taken on a neighbouring Dandelion proved to be 

 a male. It seems strange that this bee was not_ noticed at Tile 

 Hurst Wood in connection with the Sussex observations of 1911-12. 

 The nectar is easily accessible to Anthopliora pilipes, with a 

 proboscis of 19-21 mm. long ; and this bee is undoubtedly an efficient 

 pollinating agent in both types of flower. Miss Bray noticed it as 

 an occasional visitor to Primrose in Sussex; it has been seen by me on 

 them in North Wales, while I have often observed it on Cowslips at 

 Cwm, and on Primroses in Wirral, Cheshire (1919). In view of its 

 behaviour elsewhere, I have no doubt that extended observation 

 would reveal further evidence of this solitary bee as a visitor to the 

 Primrose in North Wales. The true Huinble-Bees are only erratic 

 visitors and do not devote much attention to Primroses. The nectar 

 is only accessible to the queen Bombus hortorum, whose proboscis 

 has a length of 19-21 mm., while that of the queen B. terrestris is 

 only about half as long. Although both species could easily collect 

 Primrose pollen, they show a distinct preference for other flowers. 

 As Bell (I. c.) has observed, the more numerous worker Humble- 

 Bees do not appear until later, when the Primrose season is usually 

 past. While Bombi are quite capable of pollinating the Primrose, 

 and occasionally do so, they cannot be regarded in North Wales as 

 serious agents. Scott Elliot (I. c.) records B. hortorum as a regular 

 visitor to Primroses in Dumfriesshire, but this is not the case in 

 North Wales. 



The occurrence of Oniscus asellus and Porcelho scaler ;is noc- 

 turnal visitors to Primrose flowers is of interest, as Isopoda have not 

 been hitherto regarded as agents in pollination. As they appear to 

 feed on the flowers, they may bring about autogamy in the short- 

 styled form or cross-pollination in the other type. The nocturnal 

 habits of the earwig have hitherto enabled it to evade detection as a 

 Primrose visitor ; it seems to be not uncommon at night time, when 

 it feeds on the flowers, and its behaviour shows that it may assist 

 in pollination. , . 



Gonepteryx rhamni was seen on a single occasion in Sussex, and 

 although other observers have recorded it on Primrose flowers, which 

 it can readily pollinate, in the south of England, it cannot be regarded 



