Whiteflies – Identification and Control

Last updated May 1, 2023

Identification

Whiteflies are triangular-shaped small insects with a body length of approximately 1/20 inches (2 mm).
They are white color insects.
These garden pests are active during the day.
They are social insects and live in swarms.
Whiteflies are mostly found on the lower surface of leaves.
They disperse and fly around if you shake the plant.
These pests have sucking mouthparts called stylet, which they use to suck fluids out of plants.
Larvae are oval, tiny scale-like insects.

Lifecycle

Whiteflies reproduce rapidly. They go through multiple stages before they become adults.

Stage 1 – egg
Stage 2 – instar I (crawler)
Stage 3 – instar II (immobile nymph)
Stage 4 – instar III (nymph)
Stage 5 – instar IV (pupa)
Stage 6 – adult

Whiteflies randomly lay eggs on the leaves’ underside in spirals, arks, or circles, depending on the species. The eggs hatch into nymphs which find the feeding site, flatten their body, and feed on plants sap. Nymphs undergo multiple stages until they turn into a pupa and eventually into an adult. Adults then fly off and colonize different plants. The most damage to the plants is done during their nymph stage, as they feed in large groups. There are many overlapping generations per year.

The process from egg to adult can take from 16 to 35 days, depending on the temperature and species. Whiteflies are tropical insects. Their reproduction is much faster in a warmer climate. For example, it takes 15 days for the egg to hatch at 60^oF (15.5^oC), but it only takes 3 days to hatch at 85^oF (29^oC). Therefore, their numbers are few in places that have cold winters but are very high in warm climates or greenhouses. [1]

Damage They Cause

Whiteflies suck the sap from plants and can introduce toxic saliva. As they feed, whiteflies secrete honeydew that encourages sooty mold growth. Whiteflies cause yellowing, wilting, and drooping of leaves that stun growth and eventually kills the plant.

Plants They Attack

Whiteflies can infest nearly any plant. However, their favorite hosts are:

Citrus Trees
Eggplants
Okra
Ornamental Flowers
Peppers
Sweet Potato
Tomatoes

Live Biological Control

Introduce predator insects to your garden, such as:

Lacewings
Ladybugs
Parasitic Wasps
Big-eyed Bugs
Damsel Bugs
Minute Pirate Bugs

Organic Control

Neem Oil
Citrus Oil
Insecticidal Soap
Horticultural Oil
Beauveria Bassiana

Preventive actions

Inspect plants for any whitefly infestations before you buy them.
Remove infected plant parts regularly.
Dislodge the immature pests by using a fine jet stream of water.
Trap – place a variety of plants that will attract whiteflies to protect the vital crops from harm.
Cover the susceptible plants with row covers.
Select plant varieties for your garden that can withstand pest damage.
Attract and trap them with sticky traps. Use these only in the greenhouse, as they might trap beneficial insects also. These traps will only trap flying adults.

More About Whiteflies

Adults can survive up to 3 days without plants.

These insects tend to stay on one plant until the plant becomes overcrowded. Only then do whitefly adults move to other plants. So, it is pretty easy to manage whiteflies at the beginning. It is complicated to control when they infest multiple plants. So, never wait until the damage is clearly visible. Inspect the plants regularly. The sooner you will find whiteflies, the easier it will be to control them.