Sorbus "Joseph Rock" alive with wasps?

Formosa · Hazel Tree Joined: 26 Aug 2008 Posts: 2

Hi,

I have a young Sorbus "Joseph Rock" out the back that is swarming with wasps. They are on the upper side of the leaves. Is there a sweet substance on that's attracting them or what?

As regards getting rid of them, is there any good spray. I have murdered an amount of them with the old jam jar & water technique but numbers aren't dropping.

I notice the tree is fairly infested with greenfly too.

Thanks

paddy-s · Hazel Tree Joined: 01 Aug 2008 Posts: 24 Location: Sligo

Greenfly and aphids give off a sweet sticky residue, that's why ants farm them. Leave the wasps to it, they won't harm anything.

GPI · Posted: Thu Aug 28, 2008 9:53 am Post subject:

paddy-s is spot on Formosa in saying that the infestation of greenfly and the honeydew they produce led to the wasps swarming over the leaves.
For next year, prevent a buildup of the greenfly to lessen the amounts of wasps on the tree.
For now, you can apply a drop or two of unscented washing up liquid mixed into water sprayed onto the leaves with a knapsack sprayer (cleaned, no chemicals) using the aggressive spray setting on the sprayer.
Leave this for an hour or so then repeat again to help wash off the attractant honeydew.
Some plants may be adversely effected by the chemicals in the soap, so test a leaf or two to see the reaction beforehand.
Plain water can be used on its own as well if you like.

More on aphids/greenfly here....... aphids/greenfly
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Formosa · Hazel Tree Joined: 26 Aug 2008 Posts: 2

Thanks lads. Their presence had been intriguing me. I'll give that treatment a go GPI.