Blue tailed jewel wasp

[Bruce Williams]

Stony Stratford, Bucks.

There were quite a large number of these wasps searching a 15m length of old wood fencing - almost all had red abdomens like the one in the first photo. However there was one (a little smaller) with a blue abdomen - see second photo.

Their behavior was quite interesting to watch. The top fence rails are fairly weather worn and the wood grain is quite prominent. The wasps were making their usual searching patterns but every now and again a wasps would press its whole body (not just the abdomen) flat into a depression along the line of the grain and would stay like that for several seconds. These depressions were not (as far as I could see) deep cracks but just shallow depressions about 25% as deep as their body. Any thoughts?

I know these can be difficult to id however if anyone can identify please let me know:

[eucera]

The all-blue one is Trichrysis cyanea. The only UK Chrysidid with this colour pattern

[Bruce Williams]

Thanks for the id - btw do you know if it's possible to identify gender with these wasps?

Bruce

[Matt Smith]

Originally Posted by Bruce Williams

Thanks for the id - btw do you know if it's possible to identify gender with these wasps?

You can count antennal segments (12 female / 13 male) and usually the males are a little smaller than females, but in the field there is no easy way to say male/female as you can with bumblebees for example.

[Bruce Williams]

Thanks for your help Matt - much appreciated.

Bruce