Does anybody know what are they?
Thanks.
Dina

"dina" wrote
I saw a fly 1/2 inches long, black head and legs and bright, yellow
body. It was stationary as if planting larvae(?) or doing something
else. I saw it several times on the roses. I wander how bad it is for
the roses?

Probably a Hoverfly, a predator of Aphids and good news.

--
Regards
Bob Hobden
just W. of London

"Homer Sparrow" wrote in message
...

dina;851043 Wrote:
Hi,
I wander how bad it is for the roses?



You may have been looking at a large rose sawfly. The behaviour you
saw may have been egg-laying. If so, the larvae, when they hatch,
resemble caterpillars.

Here's the adult:

http://tinyurl.com/mwmpnm


I have a pesticide-free policy in my garden, but I know that this isn't
for everyone. Treat the larvae as any other caterpillar if you want to
avoid damage to the foliage.

Homer Sparrow

Probably the effect of rain. White roses are notoriously sensitive to rain damage.