Friday, 24 April 2009

Drumboe insects

Drumboe has a very rich insect population: I find some of my most interesting species here. This is Nomada leucophthalma, which is parasitic on the mining bee Andrena clarkiella. This is yet another prime example of dependency timing: A. clarkiella uses only the pollen of willows to feed its young, and willow pollen is only available for perhaps 6 weeks of the year. So the Nomada must locate an available Andrena nest and lay its own eggs there in a very short timeframe. Nomada sp. are known as kleptoparasites: they use the pollen the Andrenas have collected for their own offspring.

This specimen was flying along the vertical earth bank looking for Andrena nests. They fly facing the bank and move sideways as they search. This behaviour can be seen for only 4 weeks of the year. Shot was manual focus!

This is an Andrena, but not the one parasitised by the above Nomada. Andrena haemorrhoa, about 15 mm long:

Smaller hoverflies are making an appearance at last. This is a male Melanostoma scalare:

The larger Eristalis pertinax has been around for a couple of weeks. This is a female:

A single Speckled Wood was the first of the year for me. I also saw one Orange tip male and a Green-veined White, both of which I showed the other day.

St. Marks Flies are so-called because they usually start to appear around St. Marks day - April 25th. They're usually pretty accurate.

I have never found a convincing identification for this one, but it should be Bibio marci.

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