Ants are a problem in any butterfly garden. We are often asked what butterfly enthusiasts can do to control ants.
We are not ant experts and can only share with confidence what has worked in our gardens in north Florida. We will also share, at the bottom of this page, what others have said has worked for them. We cannot endorse their methods of controlling ants but we are more than happy to share them with you.
In our area, fire ants are a big problem. Making large mounds, these ants can take out a large number of eggs, caterpillars, chrysalises, and adult butterflies. Other species of ants are also feasting on butterflies and moths.
Of course there are species of butterflies that benefit from ants. We have watched ants protect Gray Hairstreak and Ceraunus Blue caterpillars. The caterpillars have glands that excrete a sweet fluid (honeydew secretion) that ants drink. When the caterpillars wish to disperse the ants, they extend a pair of tentacles (eversible glands) that seem to produce pheromones that repel ants. Because ants tend to attack the caterpillar when it moves about, it is important for the caterpillar to be able to manipulate these ants.
We encourage you to read Florida Butterfly Caterpillars And Their Host Plants by Marc C. Minno, Jerry F. Butler, and Donald W. Hall. This book shares information about this ant/caterpillar relationship on pages 21 and 23.
Now out of print, Butterfly Farmer by L. Hugh Newman shares the story of the discovery of the full lifecycle of one species of butterfly that uses ants to complete their lifecycle. At a certain stage of life, ants take the caterpillars into their nest and tend to them.
Ants are drawn to some plants, like passion vine and cassia or senna plants, to drink liquid that is exuded from nodes by the leaves. Because of these nodes, ants are found on these host plants more than other host plants.
To kill ants, we use Amdro, a fire ant bait. We have found it will kill other species of ants as well. We do not know which species of ants, other than fire ants, that have died from eating Amdro at our house and farm. We do not know if it will affect crazy ants or species in your yard. We only know that it has saved many butterflies (egg through adult) in our garden and at our farm.
We have used ant poison that is used by sprinkling it on a mound and watering it well. It works well. BUT if it is used near a host plant, the poison will be drawn into the host plant and will often change the taste of the plant so that butterflies will not lay eggs on it. It will often cause the plant itself to become poisonous to caterpillars. If caterpillars are on the plant, they will die. These types of systemic poisons can stay in the plant for eight weeks or longer. Washing leaves will not remove these poisons.
We have never seen any evidence that Amdro will harm butterflies. We cannot guarantee that it will not but we have used it for over a decade at Shady Oak Butterfly Farm.
Many people have other suggestions to kill or move ants.
An internet search will bring up many methods that are suggested to kill ants, from poison to using ordinary household items.
1. Boiling water: Pour boiling water over the ant bed. We have tried this. It kills many ants but the next day we see a new mound near the old one.
2. Spread grits or cream of wheat around the mound. The theory is that when ants eat it, it will expand and explode the ant. We have not tried this method.
3. Spread diatomaceous earth (DE) around the mound. There are some reports that DE can harm caterpillars as they crawl over it. It is recommended that a mask be used when spreading DE in your yard.
4. Spread boric acid around ant beds.
5. As people send their methods to us, we will share some of them here.