The Go-Between

Tree bumblebees collecting nectar from sallow blossom this morning, beside the river Tyne at Wylam in Northumberland. They seem to be hardier than other bumblebee species, foraging despite the fact that it was cold and very windy.

Most trees that produce catkins in spring are wind pollinated but sallow relies on insect pollinators (and occasionally, perhaps, birds like blue tits that have a liking for nectar). Both male and female catkins of sallow produce nectar to attract the first bumblebees, flies and butterflies of spring. There are separate male and female sallow trees so these insect go-betweens are essential for successful seed set. The catkin above is a female and ...

..........this one is a male sallow, producing nectar and pollen. The bee has just withdrawn its proboscis from the flower (it's the brown tube with the knee-bend) and it has yet to withdraw it between the two protective sheaths that also give it rigidity: you can see the sheaths pointing upwards in a V-shape (double click image for a larger, clearer view).