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Hidden Valley Hibiscus
Growers & Hybridizers of Exotic, Tropical Hibiscus

Hibiscus Plant Care

Ants

They Seem to be Invading my Hibiscus!

We don't usually think of ants as pests of hibiscus, but controlling ants is an important part of protecting hibiscus from aphids, mealybugs, and other honeydew-producing insects. The lowly ant has a surprising ability - it can herd as well as any cowboy!  Specifically, ants carry sap-sucking insects and their eggs onto the leaves of hibiscus and then protect these sap-suckers from other predatory insects. Ants find the nectar produced by hibiscus blooms quite to their taste, then lap up the sugary honeydew that sap-sucking insects excrete onto hibiscus leaves. Do you begin to understand why there are ants running up and down your hibiscus bushes? Let me explain more.

Ants on Hibiscus Flower
Ants Marching across Hibiscus Flower to Get to Nectar
Ants will infest hibiscus just for the nectar that is produced down in the base of each flower. This sweet tasting liquid is an excellent food source for ants. It is not uncommon to pick a great looking bloom to take indoors only to discover several ants swarming over it after you do. This does not injure the hibiscus or the flower, but it is not very conducive to our enjoyment of the hibiscus that we work so hard to grow to perfection.

The way that ants do harm hibiscus is by carrying aphid eggs onto the plants. Aphids are unsightly for sure, but even worse is their ability to serve as a vector for plant viruses. The ants don't care, they are after the honeydew that aphids make from the plant sap that they ingest. So they carefully "farm" and herd the aphids like "cows" to milk them for their honeydew. Ants ferociously guard their "cows", fighting off other insect predators, like ladybugs, that could help keep the aphid numbers in check.

Another side effect of ants and their aphids is the organism, black sooty mold, which is also fond of aphid honeydew. When spores of the mold land on the honeydew, they quickly spread to cover it and the hibiscus leaf. This black mold feeds on the honeydew, not on the hibiscus leaf, and does not directly harm the plant. However, black mold looks terrible and can block the sunlight that the leaves need in order for the all important photosynthesis to take place inside the plant leaf.

How do I Control Ants?

There are three main ways to control ants in the garden. The first, our preference, is to use a bait that is taken by worker ants back to their colony where it is ingested by other ants, in particular the queen. This stops egg production and will eliminate whole ant colonies, but it takes a week or two to make a noticeable difference. However, it does provide longer-lasting control.

The second way is to spray a barrier of pesticide on the ground around the plants or around the entire garden. Such pesticides kill ants on contact and will repel them for 2-3 weeks. As soon as the pesticide wears off the ants will return though, and spraying will need to be repeated.  Most pesticides that kill and repel ants on contact can be sprayed directly on hibiscus bushes. This will also provide a good measure of success with controlling ants, but will have to be repeated every couple of weeks, or whenever ants are seen on the bushes.

Hibiscus 'Monte Carlo'
Hibiscus Flower 'Monte Carlo"
The third way to control ants is sort of a reverse strategy. Ants will usually give up eventually if the aphids or other insects they bring to your hibiscus do not thrive. Maybe they just run out of aphid eggs for awhile. In any case, if you treat your hibiscus with systemic imidacloprid containing products such as Bayers Tree and Shrub Insect Killer or Bayers 3-In-1, aphids placed on the hibiscus by ants will not be able to survive. Hibiscus plant sap contains imidacloprid after treatment, and any aphid that ingests it will stop feeding and perish before it can reproduce. This leaves the ants up a tree with no honeydew and discourages them from returning.

Organic vs. Chemical Controls

For those who are sensitive to chemicals or who prefer not to use them, there are a number of organic products available that will control ants. We use and recommend the Terro Ant Baits that contain boric acid in a sugar water solution. Also, natural pyrethrin products made from chrysanthemums are very effective against ants. Please remember that even though organically certified products are natural, they are not without some dangers if used incorrectly. It's good practice to always follow label directions when using any type of pesticide.

 

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