Common pests in your indoor garden

Common Pests

One advantage to growing indoors is that pests are less likely to find your garden. Most often, pests will be brought into your classroom through other plants or in potting soil, especially if it has been stored outdoors. Inspect plants before bringing into your home. Once a pest has established in your garden, it can be harder to eradicate without the presence of natural predators. Remember, placing sticky traps in your garden immediately upon planting is a great warning bell to let you know a pest has arrived. Act on pest issues right away!

The sight of a pest is enough to make gardeners reach for a chemical to take care of it. Growing indoors though means that we need to be more cautious with the use of chemicals as we do not want to be breathing them in in our confined spaces.

There are alternatives to chemical treatment of pests but you should prepare for repeated treatment of pests. Each method of controlling garden pests typically targets a particular stage in the pest’s life cycle. For example, if your method targets the adult pest, you will need to keep applying the treatment until all of the existing eggs have matured into adults.

What they look like

Aphids, also known as plant lice, come in different colors like gray, black and green. They cluster on the underside of leaves and suck the sap from them. They can be found anywhere on the plant, but often congregate along its stems. Like whiteflies, they excrete a sticky substance referred to as "honeydew," in which black sooty mold grows.

Symptoms

Leaves develop yellow spots, then wilt. Black mold growing on top of leaves. Aphids weaken plants by sucking the juices out of their leaves and turning them yellow.

Fungus gnats

What they look like

Adult fungus gnats are small and black with thread-like antennae, long slender legs and clear wings. Fungus gnats look similar to fruit flies. Fungus gnats lay their eggs in moist soil where the larvae will hatch and feed on small roots, fungus and other organic matter in the soil. They have no interest in fruit. If you see tiny black bugs in plant soil, and flying around your plants – those are fungus gnats. The larvae can be clear or cream-colored with shiny black heads that look like small black specks to the naked eye and grow about a 1⁄4-in. long.

Symptoms

The flying adults do not cause damage to the plant, but they lay eggs in the growing media and are a nuisance. The larvae do feed on the roots, making the plant weak and slow-growing, which can eventually lead to harm for your plants.

Mealy Bugs

What they look like

Mealybugs are tiny white bugs on houseplants, and most commonly look like white fuzzy stuff on plants leaves and stems. Mealybugs can also appear brown or cream colored, and waxy in immature stages. At first glance they don’t look like insects and are commonly mistaken for fungus or mildew rather than plant bugs. If the white bugs you see on your houseplants look more like tiny white flies that fly around when the plant is disturbed, then those are whiteflies instead of mealybugs.

Symptoms

They are piercing-sucking insects, which feed on plant sap. The insects exude a honeydew, which can cause leaves to become sticky. Ants may be attracted to the sweet liquid. In time, a black mold, called sooty mold, can grow on the honeydew giving the leaves a dirty, sooty appearance. Plants infested with mealybugs become weak, may wilt and turn yellow, and eventually die.

Spider Mites

What they look like

Spider mites, at less than 1-mm long, are tiny relatives of spiders with eight legs and oval bodies. Spider mites look like grains of sand and are found mostly on the undersides of leaves. Eggs are round and clear and become a creamy color just before hatching. If you see white webbing, you most likely have an infestation.

Symptoms

Spider mites mouth parts pierce and suck, causing damage by puncturing plant cells, resulting in fluid loss that eventually kills plants. An adult female can lay up to 20 eggs per day, causing infestations quickly.

Thrips

What they look like

Thrips are hard to see at a mere 5-mm long. They can be yellow, brown or black. To the naked eye, they look like tiny threads.

Symptoms

They leave fecal droppings on plants that appear as black spots. Females bore holes in leaves where they lay their eggs. If your garden is infested with thrips, leaves will eventually look dry—not wilted—and have yellowish spots. Look for silver or bronze colored streaks on leaves, which eventually turn brown, dry and crumbly. The pests feed by puncturing plants and sucking out the sap inside, creating the streaks.

Whiteflies

What they look like

Whiteflies resemble small, white moths and are about 1-mm long that cluster on the underside of leaves. The
nymphs are translucent and can appear to be the same color as the leaves. Like aphids, whiteflies secrete honeydew that is colonized by black sooty mold.

Symptoms

Look for stunted or twisted leaves, white spots or black moldy areas on the top of foliage. An adult’s mouth parts pierce and suck juices from plant leaves, causing white spots and yellowing. Females lay their eggs on the undersides of leaves.