Lemon tree covered in common black ants

Question

Our recently purchased potted lemon tree is covered in black ants, particularly underneath the leaves, which is causing the leaves to become droopy. The ants appear to be eating a pale coloured ‘bug’. What treatments do you recommend? We are going to wash the tree with water but I was wondering if there are any specific sprays, natural or otherwise that could be used?

Answer 1

Those bugs are almost certainly aphids, and they are causing your problems. Aphids suck the sap from the leaves, leaving a sweet substance known as "honeydew." The honeydew is highly attractive to ants. You may be able to dislodge the aphids by blasting a strong stream of water directly at the leaves. However, this sounds like a major infestation that will probably require insecticidal soap spray to kill the pests. (Most likely repeated applications.) (Avoid chemical pesticides, if possible.) These articles will help:

https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-aphids-and-ants.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/aphids-tree-disease.htm