17 February 2025

Customer Question – Aphid control in large trees?

Q. “Hi we have 3x large Hornbeam Trees across the length of our driveway, they are 2m-3m apart, come summer the obvious happens & our cars are covered in sticky residue, I’m assuming this is caused by aphids. If you agree, can you advise on the number of Ladybird Larvae Packets to buy & when, also is it work getting 1, 2 or 3 Ladybird houses to hand in the trees to support an ongoing population. We also have many trees in the garden, but three trees near a Patio rain down the same sticky substance in the summer, I think they might be a Lime, Elder (berry) & a Damson. Again thirds are similarly spaced. Thanks.” Chris Walker

A. Thanks for the message and yes its aphids – as they suck sap, they excrete the excess sugar as honeydew and this is what drips down and covers everything in a sticky mess that sooty mould will also grow on. The sticky residues and the sooty mould are often what is 1st spotted rather than the aphids themselves. 

Ladybird Larvae with release bags are the answer and as a guide we suggest the following  dependant on the truck diameter :-

• Less than 20cm, use 100 larvae and 1 release bag.
• Between 20cm and 50cm, use 200 larvae split between 2 release bags.
• Over 50cm, use 500 larvae split between 5 release bags.

Simply hoist or position the Ladybird Larvae up the tree in their release bags as soon as the 1^st sign of aphids appear. As the ladybirds eat the aphids and start to breed the aphids will be controlled. In larger trees a house is not necessary as there will be plenty of hiding places for them. I hope this helps Kind regards Jon @ Green Gardener

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