This is the ultra common Flea-beetle aka Turnip Fly. Dusting with BHC used
to be the precaution as soon as emerging~~repeated weekly until the rough
leaf stage.
This pest is only serious in dry weather and spraying with water each
evening [after sunset] is a good deterrent. Talk to other allotment
holders~~they can be most helpful.
Best Wishes Brian.
"Will" wrote in message
...
Hi All,

I think that this is my first posting here, though I have been
lurking on and off for a couple of years. I am not a knowledgeable
gardener by any means, though I used to assist my father many years
ago.

I took on an overgrown allotment the autumn before last, was
late working it last year and most of what I planted was swamped by
weeds, the exception being broad and runner beans, which both did very
well.

So I spent many hours last year hoeing, occasionally spraying
with agri grade roundup, and using an enormous flamegun to cook both
weeds and hopefully their weeds.

This year I am well in front of where I was last year, the weeds
at present are relatively few, and easily kept in check with the hoe,
and most of the allotment is planted.

I have spent some of the past three or four days admiring the
allotment, as plants have started to grow, one of which was a row of
swede, first breaking though, then getting taller and stronger. Until
today... All of the seedlings that are through are covered with very
small black beetle type bugs, and they appear to be nibbling on the
leaves of the seedlings, and/or sucking their contents out, leaving
the seedlings looking pretty poorly. Is this a known problem, and is
it readily treated?

All help appreciated...

--
Regards,

Will.