Question
Hi, Melissa;
I have two olive trees in large pots on a 5th floor balcony (in Dubai - warm climate). One is infested with ants. I don't know what kind of ant but they are black in colour and I want to know how to get rid of the ants without harming the tree. There is no food source for them (there are none in the kitchen, for instance) and being so high above the ground, I don't know why they have chosen this pot but there they are.
Advice appreciated.
Best regards

Answer
Dear Cindy, I am so sorry to be so late in sending you this answer, but in the holiday spirit my Internet server seems to be on vacation lately.  Anyway, probably what happened to get the ants up to the 5th floor is that a winged mating pair of ants flew and/or were carried by the wind and started their nest in your olive tree.  Some of the unlikely places that insects turn up can be very surprising.  At any rate, we definitely don't want to keep these ants around.  They are probably a kind of sugar or pharaoh ant (a smaller sized ant). Now since you are in a different country, I'm not always sure what chemicals are available, but I do have two solutions that should be easy to obtain.  One is orange oil.  It is very toxic to ants and if you soak some into the soil, it should kill the ants fairly quickly.  The caution on this is that you really don't want to keep the orange oil in the soil for a long time, so as soon as it seems that the ants are gone, then you need to thoroughly flush the plant with water.  Be sure to not let the plant stand in water.  The other solution is to mix boric acid with sweetened condensed milk and place it in and around the pot.  The ants will be drawn to it because of the sweetness, and the boric acid will kill them.  The caution on this is to wear a mask while you are around the boric acid so you don't inhale it.  Once again, when the ants are dead, then flush the pot out.  Oh, and one other thing: be sure to look up into the tree and see if you can see any other small bugs (I'm thinking aphids) that might be in the tree and attracting the ants.  In this case, you will need to spray the entire tree with a horticultural oil (don't use a cooking oil) once a week for about three weeks.  I doubt that you will find any in this case, however.  Now if you have trouble locating the chemicals, or if these measures don't work (in case your ants are not attracted to sweet food sources) then please write me back, so that I can fix your problem, and so that I will have more information for other clients from your area.