Hibiscus Plant Care
There are Little Specks all over my Hibiscus!
Aphids, sometimes called plant lice, are a common insect pest for hibiscus. They are visible to the naked eye and come in a rainbow of colors - black, white, and green being the most common ones on hibiscus. People who study insects tell us that there are about 4,000 different aphid species - 250 of them pests of important commercial plants.
Black Aphids on a Hibiscus Bud
Aphids feed by inserting a sharp beak called a "stylet" into the leaf, puncturing a phloem vessel which is like a blood vessel in mammals, except in hibiscus it carries the water, carbohydrates, and proteins that plants use. This "sugar water" is under pressure inside the vessel, so once it is punctured by the aphids mouthparts the liquid flows into the insect.
Aphids can reproduce very quickly, and if uncontrolled will increase in number amazingly fast. Since they tend to feed on the plant they were born on, they can quickly weaken a plant and cover its leaves with honeydew and black sooty mold that prevents sunlight from reaching the leaf. In addition, aphids can spread plant viruses to the plants they are feeding on.
Aphids have several natural enemies that feed on them, and if these are present in large enough numbers, the population of aphids is kept under control. Ladybeetles (Lady Bugs) and Lacewings are two of the predator insects that feed on aphids; however, it is not uncommon for aphids to reproduce at rates faster than natural predators can consume them.
The reproduction of aphids is strange and fascinating. Typically it goes like this: One or more eggs laid in fall will overwinter on a leaf. In spring when the weather warms up, that egg will hatch. All the newborns will be females, and those females will give live birth (not eggs) to baby aphids that are genetically identical to themselves without any involvement with a male aphid. Within a few days, these new females will also begin giving live birth to more genetically identical females. In this way aphids may go through 40 generations of reproductions within one summer. This can result in literally billions of aphids unless some are killed by predators or human intervention. In the Fall, as the temperatures drop, winged males are born. Females mate with these males and then lay the eggs that are overwintered on leaves. When food supplies dwindle winged females are born. These then migrate to other plants where the whole process begins again.
How to Control Aphids?
Green Aphids on a Hibiscus Bud
We offer two products that control aphids. The easiest to apply and longest lasting is Bayer Tree & Shrub. This is sprinkled on the soil then watered in, and lasts 3 months. We also have Bayer Advanced 3-in-1, a spray pesticide that needs to be repeated every 2-3 weeks if aphids are active and present. For this reason, in our own use at HVH, we find the systemic product, Bayer Tree & Shrub to be by far the easiest and most effective pest control product to control aphids.