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Monday, 5 October 2015

Ivy League

Ivy is starting to come into flower. Unseasonably late flowering (and hence a source of berries later on in winter), it is ever so useful for wildlife, and for an autumn small-scale mini-wildlife spectacle.

Some flower morphologies are designed for particular pollinators; in ivy the nectaries are fully exposed and open to all generalist nectar and pollen feeders. A 2013 scientific paper suggested ivy is so important it should be considered a keystone species. Some 70 moth species, 20 bugs and 12 beetles are associated with ivy, according to the BRC food plant database (Hedera helix, and this doesn't include Holly blue butterflies, and the many hoverflies, bees and wasps that visit.
Red admirals on 29 Sept 2015 ignoring Buddleia
One bee especially to look out for is the Ivy bee Colletes hederae, first recorded in Dorset in 2001, and only recognised as a separate species in 1993. It forages almost solely at ivy, so is late flying; in more sense than one, our latest solitary bee. First Devon records date from 2008 and all county records so far have been from coastal locations. This year, Ivy bee emergence started in earnest around the last week of September 2015. Hence a short train ride to Exmouth, to see what could be seen.... 
Foraging Ivy bees
Burrowing Ivy bee

This properly golden yellow and black stripey bee was conspicuous in large numbers on flowering ivy near the beach, and zooming at ankle height around areas with loose sandy soil, where they dig their burrows. One question is why they aren't found away from coastal areas in Devon (perhaps due to availability of nesting sites?) - any inland records for the county would be of great interest. Records can be submitted to DBRC and to the BWARS Ivy bee mapping scheme.

On the walk back to Exmouth station, a few Ivy bees could be seen on hedgerow ivy, but in much smaller numbers. They were joined by numerous butterflies and hoverflies, all mostly ignoring the Michaelmas daisies nearby. To emphasise the point about the range of species supported by ivy, popping up among the foliage were also some flowerheads of Ivy broomrape Orobanche hederae.

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