If you see any little white bugs flying around your vegetable plants and start to see your leaves turn yellow, you most probably are dealing with whiteflies. Whiteflies are highly damaging pests that cause massive economic losses for farmers and can similarly cause damage to your home vegetable garden.
Despite this, whiteflies have a distinct appearance and are easy to identify. Knowing how to identify whiteflies will help you control and get rid of whiteflies as soon as possible.
1. Whiteflies affect plants in the tropics, during the warm-season, and in greenhouses
Whiteflies become active when the temperature is quite warm. Because of this, whiteflies are a year-round pest in the tropics and in greenhouses. They can also be a problem in temperate areas with warm summers. Whiteflies are soft-bodied insects that are closely related to aphids and scale insects.
2. Whiteflies have a distinctive appearance.
Once you know what you are looking for it’s almost impossible to misidentify whiteflies. They are almost always white and the adults look like tiny moths. The eggs are pinpoint-sized cones that are gray or yellow in color and laid under leaves alongside adults.
The immature nymphs that come from the eggs are first mobile and then become sedentary as they molt and form a pupal stage. Unlike nymphs of other insects, they barely resemble the adults and look more like scale insects due to their disk-like appearance.
3. Whiteflies form clusters on the underside of leaves.
Whiteflies are most visible when they form a cluster on the underside of leaves. Adults, nymphs, and eggs can all be found together. The cluster may have a woolly appearance.
4. Plant leaves have yellow spots and smears
Adults and nymphs stages feed on plant sap resulting in leaves that have yellow spots and smears. The leaves eventually turn completely yellow and the plant becomes weak. This makes it easy for bacteria and viruses to attack the plant.
In addition, whiteflies may inject viruses into plants as they pierce to suck out the sap.
5. The cluster of whiteflies fly away in a white cloud when disturbed
Another distinctive way to identify whiteflies is that they all fly away creating a white cloud if you even slightly disturb them. They will slowly fly back onto the underside of the leaf afterwards.
6. Honeydew (sticky sugary secretions) left on leaves
The main component of plant sap is sugars and the excess is passed out in the form of sticky sugary secretions. These secretions, known as honeydew, are left on leaves. Honeydew can lead to other problems.
7. Ants may be seen gathered around clusters of whiteflies
Ants can be frequently found around the clusters because they ‘farm’ whiteflies to feed on the honeydew that they produced. These ants protect the whiteflies from predators and parasitoids to increase their populations preventing biological control to protect their food source.
8. Leaves and stems that look like they have been speckled or coated with a thin black film
A thin black film can sometime be seen on leaves that have honeydew on them. This is black sooty mold, a type of fungi. Black sooty mold can be wiped off as it doesn’t directly damage leaves. Despite this, the fungi may disrupt photosynthesis.
Controling and getting rid of the insects that are producing the honeydew is the best way to control the growth of the fungus. The honeydew could be falling off from another plant above. Apart from whiteflies, aphids, mealybugs and few other insects also secrete honeydew.
Once you have determined that your plants have been affected by whiteflies, you can start getting rid of them.
The damage done by whiteflies feeding on your plants itself can cause serious damage to your vegetable plants. In addition, the loss of sugars and other nutrients will make the plant very weak making it easy for diseases to develop. Whiteflies can also inject plant viruses into the plant as they pierce the plant with their mouthparts.
You should observe your plants thoroughly, at least twice a week, checking for signs of whiteflies and other pests and diseases. Check the underside of plant leaves where whiteflies and most other pests are likely to hide.
The first line of defense is to chase away the adult whiteflies and wipe off the nymphs and eggs on the leaves using a damp cloth or tissue. This must be repeated once a day for a couple of days until neither adults, nymphs or eggs are visible.
Mechanically reducing the number of whiteflies on your plants will help common predators, such as ladybugs, hoverflies, control the remaining whiteflies. Growing nectar-rich plants will help attract these predators into your garden.
If there still are quite a few whiteflies on your vegetable plants, you can spray them using a homemade pest spray such as garlic or hot pepper spray or dust your plants with dichotomous earth.
If you have tried all the options above and it still doesn’t seem to get better, you can try insecticidal soap or neem oil.
As a vegetable gardener, knowing how to identify signs of whiteflies on your plants and how these signs are related to whiteflies will help you to easily get rid of whiteflies.