POLLINATION OF THE BRITISH PRIMULAS. 127 
Examining the observations in detail, it will be found that all visiting 
insects worth considering in this connection (about thirty) may be arranged 
roughly in four groups, as follows :— 
Group 1.—Those insects, all very active and fairly large, which have 
tongues sufficiently long (not less than, say, 10mm, in length) to enable 
them to reach the nectar and, therefore, to pollinate the flowers effectively 
and in the regular manner. They, in number about fifteen, form one-third 
of all the insects known to visit the flowers. They comprise six or eight of the 
larger bees, three bec-flies, five large butterflies (which emerge from hyber- 
nation in the earliest days of spring), and one moth. 
The bees are— 
Bombus hortorum (tongue 18-21 mm.), a frequent visitor to all three species ; 
Bombus agrorum (tongue 10—15 mm.), recorded as visiting Cowslips ; 
Bombus muscorum (tongue 10—14 mm.), ditto ; 
Bombus sylvarum (tongue 12-14 mm.), recorded as visiting Oxlips ; 
Bombus lapidarius (tongue 12-14 mm.), ditto ; 
Bombus confusus (tongue 12-14 mm.), ditto ; 
Bombus (probably several other species) : 
Anthophora acervorum (tongue 19-21 mm.), a very frequent visitor to all three 
species. 
The three bee-flies are— 
Bombylius major. (tongue 10 mm.) ; Bombylius discolor (tongue 11-12 mm.) ; 
Bombylius medius (tongue —? mm.). 
All very frequent visitors, those with the longer tongues being certainly able to 
reach the nectar *. 
The five butterflies are— 
Gonepterya rhamni (tongue 18 mm.), a regular visitor, though in small numbers, 
to all three species, but especially to the Primrose. I have seen it visit all three, 
and Knuth saw it do so on one single day (26 April, 1896) in Germany. It 
has been seen visiting the Primrose in Devonshire and in Italy. Asa visitor 
to the Primrose, it is, of necessity, fairly constant ; for, when that plant is in 
flower, there are few others out for it to visit. 
Vanessa io (tongue 15-16 mm.). I have seen this as an occasional and very 
constant visitor to Primroses growing in sheltered woodland rides in Essex, 
but to neither of our two other Primulas; not recorded, I believe, by any other 
observer. ` 
Vanessa urticæ (tongue 14-15 mm.), seen by Knuth visiting Primroses (“ flying 
persistently from flower to flower”) on one occasion (21 April, 1896) in 
Schleswig-Holstein. 
Pieris brassicæ (tongue 15 mm.), one seen by Rev. E. Bell to visit Primrose ; not 
otherwise recorded. 
Pieris rape (tongue 13-18 mm.), seen once by myself on 4 April 1883, visiting 
Primrose ; not otherwise recorded. 
* See ante, p. 119. 
