Common Pests
of Indoor and Outdoor Plants
Recognition of common plant pests is essential for successful control. Most infestations are easily controlled if plants are inspected regularly and problems are caught early – early detection is critical!
Aphids:
Aphids are small, soft-bodied insects that suck juices from plants with needle-like mouthparts. They can be colored green, orange, pink, tan or black and often develop in mass within leaf whorls, axils and tender, new growth. Aphids secrete a sticky “honeydew” that accumulates on leaves and can cause the growth of sooty mold. Serious infestations can explode rapidly as the adult females are constantly producing new young. Mature Aphids develop wings and can easily travel from plant to plant.
Mealybug:
Mealybugs can be identified from their characteristic white cotton-like bodies. They colonize in hidden “nook and cranny” areas within leaf folds, around axils or around growing points. They suck juices from the plant and leave behind sticky “honeydew” that can promote the development of sooty mold. Mealybugs are difficult to wipe out completely and early detection is extremely important to save the plant.
Scale:
Scale insects are small but forceful with each species having a protective shell-like covering. Insects may be hard or soft, oval or circular, flattened or rounded that suck the plant’s juices and release a sticky “honeydew.” Scale insects are immobile but spread to other plants through “crawlers” that emerge from eggs concealed beneath adult females shells. This protective shell makes scale immune to many insecticides. The best option is using an oil to smother the insects. Be careful when applying oil.
Whitefly:
Whitefly infestations can be very difficult to control, especially on indoor plants. While young, immature insects are scale-like and attach themselves to the undersides of leaves, adults are highly mobile. Both adults and immature bugs feed on plant juices and secrete “honeydew.”
Thrips:
Thrips are tiny, slender insects that feed on leaf tissue in flowers, buds and leaves. Thrips are difficult to see, however insects might be detected by the dark spots of waste matter they leave behind on leaves. Thrips spread quickly as adults easily fly from plant to plant.
Spider Mites:
Spider Mites are extremely hard to control because of their minute size and incredibly fast rate of reproduction. They suck liquids from the plant and will produce webbing in heavy infestations.
Fungus Gnats:
Fungus gnats are generally seen on indoor plants that have been kept too wet or potted in poor mix. Adults look like small black flies while immature gnats feed on roots and decaying matter in soil.
Damage: Can damage roots
Organic Control Option: Allow soil to dry out thoroughly and repot with fresh, sterile potting mix. Use fungus gnat sticky traps near affected plant. Sprinkle Bacillus israelensis in soil and water in well.
And remember, an infested plant can be used as a hub for pests to move from one plant to another, indoors and out. Isolate infected plants if possible and treat surrounding plants with a systemic insecticide to prevent spreading an infestation. Cut off and dispose of as much plant material as possible and never compost infected clippings. Plants vary in their susceptibility to certain pests, just like certain pests have preferences for particular plants and flower colors. Plant more resistant cultivars whenever possible, especially in locations where specific pests have been a problem.
A word of warning about insecticide application: Always follow the labeled rates to limit the risk of plant damage- more is not better.
You can burn leaves with horticultural soaps and oils. These products need to be applied when the air temperature is cool. Make sure your plants are watered well before you spray and never spray wilted plants.
Try your best to ensure beneficial insects are not present when you spray. (Insecticides kill the good guys, too.)
And most important:
Just because an insecticide is listed as organic does not mean that is it safer for you, your children or pets than a synthetic, chemical insecticide. Caution should ALWAYS be taken when applying any insecticide.
Aphids:
Aphids are small, soft-bodied insects that suck juices from plants with needle-like mouthparts. They can be colored green, orange, pink, tan or black and often develop in mass within leaf whorls, axils and tender, new growth. Aphids secrete a sticky “honeydew” that accumulates on leaves and can cause the growth of sooty mold. Serious infestations can explode rapidly as the adult females are constantly producing new young. Mature Aphids develop wings and can easily travel from plant to plant.
- Damage: Yellowing, stunting and wilting of affected plants
- Control: Spray plants with a Permethrin product once a week
- Organic Option: Pyrethrin or Insecticidal Soap
Mealybug:
Mealybugs can be identified from their characteristic white cotton-like bodies. They colonize in hidden “nook and cranny” areas within leaf folds, around axils or around growing points. They suck juices from the plant and leave behind sticky “honeydew” that can promote the development of sooty mold. Mealybugs are difficult to wipe out completely and early detection is extremely important to save the plant.
- Damage: Stunted growth, wilting, yellowing and leaf drop of plants
- Control: Spray plants with Acephate every 2 weeks
- Organic Option: Cut off and dispose of infected growth. Spray plants with a combination Neem oil/Pyrethrin product
Scale:
Scale insects are small but forceful with each species having a protective shell-like covering. Insects may be hard or soft, oval or circular, flattened or rounded that suck the plant’s juices and release a sticky “honeydew.” Scale insects are immobile but spread to other plants through “crawlers” that emerge from eggs concealed beneath adult females shells. This protective shell makes scale immune to many insecticides. The best option is using an oil to smother the insects. Be careful when applying oil.
- Damage: Stunt growth, wilting, yellowing and death of plants
- Control: Horticultural Oil, Acephate when in crawling stage
- Organic Option: Neem Oil
Whitefly:
Whitefly infestations can be very difficult to control, especially on indoor plants. While young, immature insects are scale-like and attach themselves to the undersides of leaves, adults are highly mobile. Both adults and immature bugs feed on plant juices and secrete “honeydew.”
- Damage: Distorted, yellow and dried-out leaves on affected plants
- Control: Spray plants with Permethrin product once a week
- Organic Option: Spray plants with Caption Jack’s Dead Bug Brew once a week
Thrips:
Thrips are tiny, slender insects that feed on leaf tissue in flowers, buds and leaves. Thrips are difficult to see, however insects might be detected by the dark spots of waste matter they leave behind on leaves. Thrips spread quickly as adults easily fly from plant to plant.
- Damage: Leaves can become streaked, as if rubbed by sandpaper and foliage and flowers can become silvery and dried out
- Control: Spray plants with Acephate every 2 weeks
- Organic Option: Spray plants with Captain Jack’s Dead Bug Brew once a week
Spider Mites:
Spider Mites are extremely hard to control because of their minute size and incredibly fast rate of reproduction. They suck liquids from the plant and will produce webbing in heavy infestations.
- Damage: Leaves become stippled, dry out and die
- Control: Spray plants with a Permethrin product once a week
- Organic Option: Spray plants with a combination Neem oil/Pyrethrin product
Fungus Gnats:
Fungus gnats are generally seen on indoor plants that have been kept too wet or potted in poor mix. Adults look like small black flies while immature gnats feed on roots and decaying matter in soil.
Damage: Can damage roots
Organic Control Option: Allow soil to dry out thoroughly and repot with fresh, sterile potting mix. Use fungus gnat sticky traps near affected plant. Sprinkle Bacillus israelensis in soil and water in well.
And remember, an infested plant can be used as a hub for pests to move from one plant to another, indoors and out. Isolate infected plants if possible and treat surrounding plants with a systemic insecticide to prevent spreading an infestation. Cut off and dispose of as much plant material as possible and never compost infected clippings. Plants vary in their susceptibility to certain pests, just like certain pests have preferences for particular plants and flower colors. Plant more resistant cultivars whenever possible, especially in locations where specific pests have been a problem.
A word of warning about insecticide application: Always follow the labeled rates to limit the risk of plant damage- more is not better.
You can burn leaves with horticultural soaps and oils. These products need to be applied when the air temperature is cool. Make sure your plants are watered well before you spray and never spray wilted plants.
Try your best to ensure beneficial insects are not present when you spray. (Insecticides kill the good guys, too.)
And most important:
Just because an insecticide is listed as organic does not mean that is it safer for you, your children or pets than a synthetic, chemical insecticide. Caution should ALWAYS be taken when applying any insecticide.