Question
QUESTION: Ants climbing up and down my grape fruit tree and crawling inside it and back out. Its an old tree, how old I do not know, but it was full grown when i moved here 22 years ago. If ants not hurt it, then I will leave alone. Should i be concerned?

pa

ANSWER: There are several types of ant that will crawl on trees. Some are just gathering honeydew from aphids and cause no problem with the tree. Other like the carpenter ant will build nest in hollow trees and excavate the wood which could weaken the trunk. In the case of ants just crawling on the limbs and trunk you can use any type of any spray and eliminate the ants. I would also use an ant bait type insecticide around the tree this will be carried back to the nest and kill the nest.

Carpenter ants nest in trees in one of two situations: 1) in rotted, decayed wood or 2) in the center heartwood section of the tree. In neither case are they harmful to the tree. Control is unnecessary for the tree's health, as the ants are taking advantage of preexisting soft, weak wood to establish their colony. Insects, disease, or environmental conditions such as drought are often responsible for weakening and killing limbs or sections of trees. This allows wood rot to set in, which results in wood decay, giving carpenter ants the opportunity to colonize the tree. Carpenter ants use knots, cracks, holes, and old insect tunnels to gain access to these areas. If there is evidence of this, the best control is to bait the colony.

Most retail products are liquid or granular formulations containing hydramethylnon, sulfluramid, abamectin, or boric acid. An inexpensive liquid bait of 1% boric acid in a 10% sugar water solution can be mixed at home, but it is very slow acting and must be constantly replenished. Baits vary a great deal in their effectiveness. Carpenter ants have complex food preferences, and some of the sugar-based baits will not be attractive to the ants long enough to be successful




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QUESTION: I still do not know what to do. I do not like killing and I dont know if these ants hurt my tree. They are very small ants, but I dont know what kind. Can I send a picture? And poison would effect the grapefruits that we eat. Some one else recommended Neem oil as non poison and is repulsive to ants, so they leave. The only Neem that I can find is 70% and 30% other non listed ingredients and it said on the bottle keep of clothes, skin and do not let it get into ground water. That sounds like poison.

Answer
I would spray the trunk with an insecticide called Malathion. It is a contact insecticide and can be washed off any fruit it might get on without harming anything. I would also treat around the tree with one of the commercial ant baits--this will be picked up by the ants and carried to their nest killing the ants there. This will not be absorbed by the tree and will not get into the fruit. Both of these insecticides are harmful to insects but not humans.