Yes, Elephants are afraid of ants most especially the Elephants in Africa. Research shows that Elephants avoid trees that have ants on them. With the aid of their sensitive trunk which has many nerve endings, Elephants are able to detect tress that have ants on them.
Acacia drepanolubium is a species of plant that is commonly avoided by Elephants because the plant has swarms of ants on them. The Acacia has a sweet substance that attract ants. This also serve as an opportunity for the plant to be protected from herbivores like the Elephants.
It is amazing to know that the smallest animal can terrify the largest animal in the world.