io6 
E. & H. Drabble. 
Natural History ”) and Packard, but it may be mentioned that 
the extended “trunk” differs greatly in length in different species. 
It is stated that in Rhingia it may be as long as 11-12 mm., and 
in Syrphus balteatus as short as 2 mm. 
Knuth mentions Circaea lutetiana, Veronica Chamcedrys and 
V. Beccabunga as typical “hover-fly” flowers, hut our observations 
shew, that although these may be visited frequently, many other 
flowers, quite differently adapted are much more generally fre¬ 
quented by these flies. Knuth also says that the Syrphidae are 
specially attracted by “ social flowers.” They certainly do 
visit such flowers freely, for example, Heracleum, Leontodon, 
Hieracium, Senecio and Aster, but according to our experience they 
seem to be very generally attracted by flowers that can hardly be 
described as “ social.” Thus, we have found Rubus to be the most 
attractive of all the flowers at which we have worked, as regards 
both species and actual number of individual visits. The com¬ 
paratively slight reference to Rubus in this connection by Knuth is 
surprising. Convolvulus arvensis, an entirely non-social flower, is 
also freely visited. 
As far as our experience goes, the flowers principally visited 
are as follows :— 
Ranunculus acris L., R. repens L., R. Flammula L. Flowers 
not aggregated. Visited for nectar and pollen. A nectary lies near 
the base of each petal and is covered by a small scale. Much 
pollen is shed from the extrorsely dehiscing anthers, the outermost 
of which shed their pollen before the stigma is receptive. 
Rubus spp. Visited for nectar and pollen. The nectar is 
produced on a thalamal disc internal to the stamens, and the 
insect has to push the stamens apart to reach it. 
Heracleum Sphondylium L. Flowers aggregated. Visited for 
nectar, which is produced on an open epigynous disc. 
Senecio Jacobcea L., Aster spp. (various kinds of Michaelmas 
daisy), Chrysanthemum Leucanthemum L., Tanacetum vulgare L., 
Leontodon autumnale, Hieracium boreale Fr., Taraxacum officinale 
Weber, Sonchus asper Hill. Flowers aggregated. Visited for nectar, 
which is produced on an epigynous disc and wells up into the 
tube of the corolla. 
Convolvidus arvensis L. Flowers not aggregated. Visited for 
nectar. Nectaries covered by the broadened bases of the filaments, 
which leave five narrow passages. 
The following table shows the Syrphid visitors to the flowers 
of fourteen species observed by us during the summer of 1916. 
