On 12/08/2011 21:01, NT wrote:
I had a mass of blackfly eating a plant, and had run out of spray, so
decided to reduce their numbers temporarily by blasting them with a
hose pointing upwards. When I returned to spray a couple of days
later, there was no more damage and no blackfly. Is this pure
coincidence, or is this really effective at wiping them out?


NT


It is really effective. The 'coincidence' is that when water coincides
with their breathing tubes, they drown and die. A few may just get
knocked from the plant to crawl elsewhere, but you'll squirt them next
time.

You don't even have to get the hose out. A spray bottle with water will
be just as effective and waste less water (unless you're irrigating
anyway). A tiny drop of detergent will be even more effective.

It is important to note, though, that this method is just as effective
on beneficial insects like bees, hoverflies, ladybirds, et al. :@(

--
Spider
from high ground in SE London
gardening on clay