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Notice Pests in Your Indoor Garden? Read This!
Pests are crafty little creatures. They can enter the home through open windows, new houseplants from garden centres or even fruits and vegetables from the grocery store.
The fact that smart gardens are ecologically clean means they can sometimes be a tempting place for pests to live. If you suspect any of these common pests have been feasting on your plants, do not worry. Nothing is lost if you notice the insects before they form a large colony. Here’s your comprehensive guide to recognising and controlling them.
1. Aphids
Identifying
Aphids have tiny, pear-shaped bodies with long antennae; the nymphs look similar to adults. Most species have two short tubes projecting from their hind end. Various species can appear to be white, black, brown, gray, yellow or light green. Adults may or may not have wings.
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Nymphs and adults feed on plant juices. They attack leaves, stems, buds, flowers, fruit, and/or roots, depending on the species. Look for misshapen, curling, stunted, or yellowing leaves and new buds that are deformed. Be sure to check the undersides of leaves; aphids love to hide there. If the leaves or stems are covered with a sticky substance, that’s a sign that aphids may have been sipping sap.
Options for controlling
- Wash them off under running water, monitor the plant and repeat if necessary.
- Ethanol spray - Make a spray mixture (75 percent of alcohol (ethanol 40%) and 25 percent of water).
- Neem oil - It inhibits insect nutrition and fertility, therefore life cycle will be disturbed. Follow the package instructions for diluting the oil in water and spray the affected areas. Repeat if necessary. Although neem oil is of natural origin, wait a few days after spraying before eating your plants.
2. Thrips
Identifying
Thrips are tiny, slender, yellowish / blackish insects with fringed wings. They are typically found on leaves and between flower petals. The adults are very difficult to see without a magnifying lens.
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Both adults and nymphs (immature stage) feed by scraping surface cells to suck plant sap. Leaves fed on by thrips will often take on a silvery or speckled appearance. As thrips are very tiny, it’s hard to see them with the naked eye. For this reason, it’s very important to monitor the plant closely - if there are silvery spots on leaves, it’s probably thrips damage. It can be managed when detected at an early stage.
Options for controlling
- Mechanical control - In the early stages, pinch off damaged leaves with silvery spots to avoid nymphs growing and making a whole new colony.
- Neem oil - It inhibits insect nutrition and fertility, therefore life cycle will be disturbed. Follow the package instructions for diluting the oil in water and spray the affected areas. Repeat if necessary. Although neem oil is of natural origin, wait a few days after spraying before eating your plants.
- Blue sticky traps - helpful for monitoring adult populations.
- Biological control - Amblyseius swirskii are thrips’ natural enemies.
- Discarding the plants - With a heavy infestation, it may be necessary to discard the plant, disinfecting the garden. Wait 1-2 weeks before plugging in new soils to avoid pests’ life cycle continuing.
3. Fungus Gnat
Identifying
Adult fungus gnats are delicate in appearance. They can often be seen running across or flying near the soil surface of a houseplant. They are weak flyers and are attracted to light.
The larvae are small worm-like creatures up to 1cm long with shiny black heads. If you look closely at the top of the soil, you may notice tiny (almost transparent) larvae. It's hard to spot them, though, as they tend to exist mostly under the soil.
Images: Shutterstock & Leanne Pundt
The larvae generally feed on decaying organic material or fungi growing in the soil. The larvae of some species will also feed on roots. This feeding is especially damaging to very young plants. With older, established plants, the initial sign of an infestation is that the plant loses its normal healthy appearance.
Options for controlling
- Dry conditions - remove soil and let them almost dry out (until first signs of plant withering) and plug them in the garden again. Dry conditions will kill the larvae.
- Yellow sticky paper - helps monitor and keep down the number of fungus gnat adults but does not solve the issue entirely.
- Hydrogen peroxide - mix one part of hydrogen peroxide (3%) with four parts of water and add it to the tops of all the soils. Be careful not to burn young plant roots with a mixture that’s too strong! It can also be added to a water tank to prevent mosquitoes.
- Biological control - Hypoaspis miles are Fungus gnats’ natural enemies.
4. Spider Mites
Identifying
Mites are not insects but are more closely related to spiders. Since they are extremely small, plant damage is typically the first sign of their presence. A silky web is often seen with heavier infestations.
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Both spider mite adults and their immature forms damage plants by sucking plant sap. Damage includes light-coloured speckling on the upper surface of leaves and results in a plant with an overall faded look. If the mites are left unchecked, leaves become bronzed or yellowed and the plant dies. Spider mites are usually more of a problem on house plants that remain indoors year-round.
Options for controlling
- Neem oil - It inhibits insect nutrition and fertility, therefore life cycle will be disturbed. Follow the package instructions for diluting the oil in water and spray the affected areas. Repeat if necessary. Although neem oil is of natural origin, wait a few days after spraying before eating your plants.
- Discarding the plants - With a heavy infestation, it may be necessary to discard the plant, disinfecting the garden. Wait 1-2 weeks before plugging in new soils to avoid pests’ life cycle continuing.
5. Mealybugs
Identifying
Mealybugs are small, pale insects related to scales and they move very sluggishly. The adult females cover themselves and their eggs with a white, waxy material, making them look cottony. Nymphs look like adult mealybugs, only smaller. The wax on mealybugs helps repel pesticides and makes them somewhat difficult to control. Mealybugs are most commonly found on the lower surfaces of leaves and in leaf axils (where the leaf attaches to the stem).
Images: Shutterstock
They suck plant sap, causing stunted and distorted growth and sometimes plant death. Like aphids, mealybugs excrete honeydew, providing the opportunity for growth of sooty mold fungi.
Options for controlling
- Mechanical control - light infestations can be controlled by removing individual mealybugs by hand.
- Ethanol - wiping each insect with a cotton swab dipped in rubbing alcohol - 75 percent of alcohol (ethanol 40%) and 25 percent of water.
- Neem oil - It inhibits insect nutrition and fertility, therefore life cycle will be disturbed. Follow the package instructions for diluting the oil in water and spray the affected areas. Repeat if necessary. Although neem oil is of natural origin, wait a few days after spraying before eating your plants.
- Discarding the plants - With a heavy infestation, it may be necessary to discard the plant, disinfecting the garden. Wait 1-2 weeks before plugging in new soils to avoid pests’ life cycle continuing.