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Identifying and Eliminating Common Houseplant Pests

Posted April 22nd, 2016 by Robin Nichols in

Aphids

Identification

Aphids are tiny soft-bodied pear shaped insects that can be black, yellow, green, or brown. They are often Aphidsdifficult to see until large colonies have formed. Unlike other insects, aphids are mostly female, can reproduce without mating and give birth to live offspring rather than laying eggs. These females can produce up to 100 daughters in a lifetime and the daughters can start reproducing within 6-8 days of their birth. Aphids cause damage by sucking the sap out of a plant; they especially like the stems, new growth, the underside of leaves, and flower buds. This sap removal causes curling and crinkly leaves and ruins flower buds. Aphids can also serve as a vector in transmitting viruses from plant to plant. As they feed, aphids secrete a sticky waste product called “honeydew.” This honeydew acts as breeding ground for sooty black mold and encourages ants to infest the plant. Black mold ruins the appearance of a plant, retards growth, and prevents photosynthesis. Aphids are difficult to see and reproduce rapidly, so it’s really necessary to check your plant weekly to prevent a major infestation.

Elimination

If aphids appear on a leather-leafed plant, spray the green solution (equal parts alcohol and water, a few drops of liquid biodegradable soap, and a few drops of mineral oil) or a commercial product called neem oil on all parts of the plant. For furry leafed plants, like African Violet, use a mixture of warm water, a few drops of mineral oil, and a few drops of liquid biodegradable soap.

Fungus Gnats

Identification

This small dark skinny pest flies and jumps around plants and people. Fungus Gnats develop in soggy potting soil, feeding on root hairs and emerging as adults every 30 days.

Elimination

The best way to eliminate Fungus Gnats is to allow the soil to thoroughly dry out. This eliminates the eggs and gnats in the pot. You can use Yellow Sticky cards to trap the Fungus Gnats that are flying around.

Mealy Bugs

Identification

Mealy Bugs are one of the most annoying and destructive pests that attack houseplants. A female mealy bug is capable of laying over 500 eggs in less than 2 weeks. These tiny sucking insects look like small pieces of cotton scattered on your plant. When young, mealy bugs have legs and can crawl; this is the best time to treat an infestation. These pests cause damage by sucking the sap out of a plant, concentrating especially on the tender new growth causing spots on the leaves, yellow leaves, leaf drop, slow growth and weak stems. While feeding on the plant, mealy bugs, like aphids, secrete that sticky substance called “honeydew” which acts as a breeding ground for “sooty black mold.” This mold covers leaves and stems ruining the plant’s appearance and interfering with photosynthesis.

Elimination

When mealy bugs are immature and crawling, it is best to use sticky cards to trap them. Once they mature, Mealy Bugs should be sprayed with the green solution (equal parts alcohol and water, a few drops of liquid biodegradable soap, and a few drops of mineral oil) or a commercial product called neem oil. Be sure the plant is well watered and not in the sun when you spray. Repeat this treatment every 10 days for a month to catch any further eggs that might hatch. On furry leafed plants such as African Violets, dip a Qtip in the green solution and wipe the mealy bugs off. Do not spray the entire leaf.

Scale

Identification

Soft Brown Scale is the most common scale that attacks indoor houseplants. They are especially attracted to ficus, ivies, spider plants, ferns, aralias and scheffleras. Scale will appear as small bumpy slow moving brown spots. As the scale sucks on the sap of the plant it secretes honeydew which attracts sooty black mold.

Elimination

Because of its shell-like exterior, sprays are only partially effective against scale. You need to wipe off the lines of brown oval bumps with your finger, a cloth, or a child’s toothbrush then spray the plant with neem oil. Use green solution to clean off the black mold.

Whitefly

Identification

This small gnat-like insect, covered in a powdery white wax, feeds on the sap of all types of plants. This causes leaf-drop and eventually weakens the entire plant. While feeding, Whiteflies also secrete “honeydew”. The flying adults lay eggs on the tops of leaves, but it is the immature nymph stage, that feed unnoticed on the underside of the leaves, that do the real damage.

Elimination

Sticky cards are a good way to trap the flying adults and prevent new eggs. Spray green solution to get rid of the feeding nymphs on the underside of the leaves; for furry leafed plants, like African Violet, use a mixture of warm water, a few drops of mineral oil, and a few drops of liquid biodegradable soap.

Want more information? Try these articles:

5 Great Smelling Houseplants

11 Houseplant Propagation Tips

Natural Pest Control for Greenhouses and Indoor Gardens

Natural Pest Control for the Greenhouse and Garden

Top Houseplants for Improving Air Quality

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