The butternut squash in the back garden is infested with blackfly.
We have put a couple of ladybirds on it in the past, and today I noted two
ladybirds on the plant wandering about in a slightly dazed fashion (although
one was a 'black with red dots' so not one we had introduced).
However given the number of blackfly a couple of ladybirds are as likely to
have a visible impact on the total numbers as a small child with a teaspoon
is on ten tons of jellybeans.

I've left it alone thus far as I expected natural predators to multiply and
feed off the enormous area of free food.
However this has not happened.

I've just given roughly half the plant a spray with soapy water to see if
that will clear the leaves and stems.
I've left the other half just to see how much difference the soapy water
makes.
No other plant in the garden seems to be infested, and certainly not to this
level.

Any idea how long the soapy water takes to act, and if the blackfly drop off
or just die 'in situ'?
And if so, how do you tell that it is working??

Cheers

Dave R
--
No plan survives contact with the enemy.

Helmuth von Moltke the Elder

In article ,
David WE Roberts wrote:
The butternut squash in the back garden is infested with blackfly.
I've left it alone thus far as I expected natural predators to multiply and
feed off the enormous area of free food.
However this has not happened.

It rarely does. Blackfly breed MUCH faster than their predators.

I've just given roughly half the plant a spray with soapy water to see if
that will clear the leaves and stems.
I've left the other half just to see how much difference the soapy water
makes.

You need to soak all surfaces, and they will walk from one part
to the other.

No other plant in the garden seems to be infested, and certainly not to this
level.

That's common. I am a little surprised that it's blackfly on a
cucurbit, though - this year's similar event for me was red spider
mite on a Brugmansia and a courgette (both of which are very prone
to RSM).

Any idea how long the soapy water takes to act, and if the blackfly drop off
or just die 'in situ'?
And if so, how do you tell that it is working??

In dry weather, they shrivel up in situ within 24 hours. In wet
weather, you can tell because they stop moving when prodded gently.


Regards,
Nick Maclaren.

David WE Roberts wrote:
The butternut squash in the back garden is infested with blackfly.
We have put a couple of ladybirds on it in the past, and today I noted
two ladybirds on the plant wandering about in a slightly dazed fashion
(although one was a 'black with red dots' so not one we had introduced).
However given the number of blackfly a couple of ladybirds are as likely
to have a visible impact on the total numbers as a small child with a
teaspoon is on ten tons of jellybeans.

I've left it alone thus far as I expected natural predators to multiply
and feed off the enormous area of free food.
However this has not happened.

I've just given roughly half the plant a spray with soapy water to see
if that will clear the leaves and stems.
I've left the other half just to see how much difference the soapy water
makes.
No other plant in the garden seems to be infested, and certainly not to
this level.

Any idea how long the soapy water takes to act, and if the blackfly drop
off or just die 'in situ'?
And if so, how do you tell that it is working??

Cheers

Dave R

I've found a wet paintbrush to be as effective as anything, if a little
time consuming :-)

In article , David WE Roberts
writes
The butternut squash in the back garden is infested with blackfly.
[snipped]

Any idea how long the soapy water takes to act, and if the blackfly
drop off or just die 'in situ'?
And if so, how do you tell that it is working??

I had an infestation of blackfly on a couple of my broad bean plants,
and sprayed them with soapy water, which did the trick. They didn't drop
off but died in situ and the plant recovered slightly.

I suppose it depends what you mean by soapy water. The idea is that when
the water evaporates the remaining deposit coats the little beasts and
chokes them. However, using something like Fairy Liquid, which is
designed for washing dishes and leaving little or no deposit, is not so
effective as proper soap.

I used shavings of toilet soap to make up a strong solution which
appeared to work very well.

Roy.

--
Roy Bailey
West Berkshire.

Incidentally, I checked last night, and it's only the beans with the red
flowers that are really suffering from blackfly. Those with white/cream
flowers and those with purple flowers seem unaffected. The Painted Lady,
which have partial red + white flowers are slightly affected.