Spider mites are small, eight-legged arachnids that are a common pest on indoor, outdoor, and greenhouse plants. They can be difficult to control, as they reproduce very quickly. The life cycle of a spider mite is as follows:
Egg: The female spider mite lays her eggs on the underside of leaves. The eggs are usually white or yellow, and they are very small, about the size of a pinhead.
Larva: The eggs hatch into larvae. The larvae are very small and pale, and they have six legs. They feed on the sap of the plant, and they molt twice to become nymphs.
Nymph: The nymphs are slightly larger than the larvae, and they have eight legs. They feed on the sap of the plant, and they molt twice to become adults.
Adult: The adults are the most common stage of the spider mite life cycle. They are about the size of a dust mite, and they are usually red, orange, or yellow. The adults feed on the sap of the plant, and they can live for about two weeks.
The entire life cycle of a spider mite can take anywhere from two weeks to two months, depending on the temperature and humidity. Spider mites can reproduce very quickly, and a single female can produce hundreds of eggs in her lifetime. This means that an infestation can quickly get out of control. It also means that even when you think they are gone, maintenance/prevention sprays are a good idea. There have been endless accounts of people knocking down an infestation and stopping treatment, only to have them come back again and again because some eggs or a single female mite was missed.
Key Environmental & Growing Controls:
Spider mites thrive in dry conditions with low humidity
Keep plants properly watered. Some people insert fingers into soil to first knuckle, others lift the pot/grow bag, others use a moisture meter, and others use various passive or automated watering. Whatever method you choose, make sure you consistently water (but don't over water!) when your soil starts to dry out.
Fertilize your plants: weak plants are susceptible to pest and fungal attacks as they aren't strong enough to fight back. Next to watering issues, lack of proper nutrients can really weaken a plant and cause deficiencies - which then lead to infestations. Look up your plant's fertilization requirements, and if you start seeing issues like yellowing/spots immediately investigate to determine if there is a deficiency or pest attack (as they can look similar at times)
For indoor or greenhouse growers, keeping proper humidity levels and vapor pressure deficit (VPD) keeps plants healthy and helps them fight off infestations
The early signs of spider mites infestation are often subtle. You may notice:
Tiny white or yellow spots on the leaves of your plant
Silky webs on the undersides of leaves.
Leaves that are curled or distorted.
Leaves that are dropping prematurely.
A general decline in the health of your plant.
If you see any of these signs, it is important to check your plant carefully for spider mites. You can do this by using a magnifying glass to look for the mites themselves. They are very small, but they can be seen as tiny moving dots on the leaves.
There are a number of ways to control spider mites. Some common methods include:
Prevention spray: This is the best approach as preventing attacks is always easier (and cheaper) than fighting. Plant Bodyguard spray weekly can repel and prevent spider mites as well as a variety of other pests and mold/mildew.
Physical removal: You can remove spider mites by gently wiping the leaves of your plant with a damp cloth. This will remove any visible mites, but it will not kill the eggs.
Insecticidal soap/spray: Plant Bodyguard is a natural organic spray made to fight spider mites at all stages without hurting beneficial insects like lady bugs and bees. Spray every 3 days until no mites can be found, and then continue with weekly sprays for prevention.
Beneficial insects: There are a number of beneficial insects that can help to control spider mites. These include ladybugs, lacewings, and predatory mites. You can purchase these insects from most garden centers or online.
If you have a severe spider mite infestation, you may need to use a combination of methods to get rid of them. It is important to start treatment as soon as you see spider mites, as they can reproduce very quickly - then continue weekly maintenance for prevention.