Friday, April 06, 2007

Has anyone else observed this Hoverfly?

The main picture here shows the Hoverfly Eristalis pertinax taken on the 28th March.

This is a common species found in gardens wherever there are suitable flowers. It is very easy to spot at this time of the year even if you are unable to get close enough to identify it. This is because the male hovers at about a 1 metre height, seemingly away from any flowers, where it vigorously defends its territory of a few square metres. Periodically it then seems to suddenly jerk up into the air anything up to 5 metres high before returning again to its original position. Another curious phenomenon that I have noticed with this species, is that it apppears to have its landing gear permanently at the ready.

It appears to be very curious with us humans, and if we enter their territory they come quite close and have a gander. Please have a look now in your garden on a sunny day and tell me if you spot the same behaviour patterns.

Out of interest, I have been able to identify this particular Hoverfly from 3 observations shown in these photographs.

1. The main picture shows tergite 2 with triangular orange markings. The rest of the tergites are black. (The Tergites are segments that appear on the abdomen. The number of visible segments depend on the subfamily).

2. The second picture shows the front leg with the tarsus entirely orange, even on the last two segments.
(The Tarsus consists of five small segments). The black section in the picture is the Tibia.

3. The third picture shows the strong downwards loop in the centre vein. For interest, this is referred to as vein R4+5.