Tuesday, 16 July 2013

Eyes on the bramble

The bramble is alive with insects at the moment, its flowers the lure that attracts flies, beetles and a multitude of bees. Although many of the visiting insects are familiar enough it is always worth spending some time at a flowering bramble to see what else might be attracted in. Over the years, for example, bramble has provided me with some of my best views of white admiral and black hairstreak butterflies, not to mention several interesting species of beetle.

Today though, it is the commonplace insects that are my focus, the bramble providing an opportunity to brush up on my bumblebee identification and to try out a new identification ‘app’ developed for the ipad by TouchPress . The most common bumblebee on this particular patch of bramble is the tree bumblebee Bombus hypnorum, a recent colonist whose populations here in the Brecks appear to be going from strength to strength. This attractive bee was first recorded in Britain back in 2001 but was not recorded from Norfolk until 2008, when an individual was found in Earlham Cemetery. Being one of the easier bumblebees to identify, with (in queens, workers and most males) a ginger thorax, black abdomen and white ‘tail’, you stand a good chance of spotting one this summer here in Norfolk. Tree bumblebees, as the name suggest, usually nest above the ground in holes in trees or buildings. They have also taken to using nest boxes of the type erected for hole-nesting birds like blue or great tit.

The arrival of the tree bumblebee is perhaps unsurprising given that its distribution elsewhere in Europe sees it established as far north as the Arctic Circle. The colonies of this species can be sizeable with perhaps as many as 200 workers supporting them, which might explain the numbers that I am seeing here on the bramble where they outnumber the white-tailed and buff-tailed bumblebees flying alongside them. Some of the other bees present will need more careful scrutiny, however, if I am to pick out some of the cuckoo bumblebees that might be present. Cuckoo queens take over the nests of true bumblebees, ousting the resident queens to secure the labour of their workers, which then help to raise cuckoo males and females.

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