"Stan The Man" wrote
My garden (and home) is being invaded by horse flies (three horses are
stabled in the field next door) and their nasty bites make venturing
out into the garden quite hazardous. Is there anything I, or the horse
owner, can do to reduce their number?

Not reduce their numbers but to stop you and yours being bitten try using an
insect repellent containing DEET. Most good outdoor shops will stock the
real stuff if your local chemist doesn't.

--
Regards
Bob Hobden
17mls W. of London.UK