Wednesday, 25 July 2018

A couple of solitary wasps

Oh dear.  I thought bees were bad enough with 275 UK species but now I read there are around 9000 species of wasp in this country.  Here are two I have seen in the garden recently -  so only 8998 to go.

We have only seven species of social wasp (such as the common wasp, Vespula vulgaris) and all the rest are solitary, meaning that there are no workers and each female lays eggs in her own nest (or someone else's - see below).  I have three standing dead sycamores near the front door and last winter I drilled some 8mm holes in them.  When I checked recently I found most were occupied by wasps.  I think this one is an Ectemnius species, of which we have 10 in the UK.  Although I drilled a straight hole the wasp will make up to a dozen side burrows, each ending in a cell in which she lays an egg and provisions it with 6-12 flies for the larva to eat.




Two thirds of all the UK wasp species are parasitic, laying eggs in the larvae or pupae of the host insect.  Some are even hyperparasites, preying on other parasites.  This little beauty is a ruby-tailed wasp and is a kleptoparasite of solitary bees and wasps, meaning it lays its eggs in their nests and its larvae eat the host egg or larva and all the food in the cell.  It is probably Chrysis ignita, although there are several similar species.  It is only about 8mm long and runs around the wall checking for holes containing a possible host, so photographing it isn't easy.

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