Houseplant Pest Management

Posted: February 11, 2013

Plants that are not vigorously growing and are under stress may be particularly susceptible to insect and mite injury.

Houseplant pests can cause extensive damage to the appearance and the health of your indoor plants and can also be simply a major nuisance for the gardener.  Plants that are not vigorously growing and are under stress may be particularly susceptible to insect and mite injury.

Infestations of mealybugs and whiteflies are mostly due to the gardener introducing a new plant into the indoor house garden.  It is very important to make a new plant quarantine area away from your current houseplants and leave the new plants in that area for at least a three week period.  You then need to do a very careful inspection of those new plants before you introduce them to other houseplants in your home.

If a pest infestation is found on a houseplant there are several options for control measures.  Syringing the plant with a vigorous jet of water is effective for the control of spider mites and aphids which are easily dislodged.  Large houseplant insects are easily controlled by handpicking.  This is especially useful for scale insects and mealybugs.  If you have whiteflies you can use a small hand held vacuum on the plants, just be care with the strength of the suction on smaller plants.  There are yellow sticky traps that are useful on pest that fly, these include whiteflies, winged aphids and fungus gnats.  These traps are sold commercially or you can easily make them by cutting bright yellow cardboard and covering them with petroleum jelly.  These sticky traps are not as effective with the young life stages of most pests because during the early period of the insects’ development they tend to stay on or close to the plant.   Insecticidal soaps are one of the most commonly used houseplant insecticides used in the home today.  These are used as dilute sprays and can help control many houseplant insects and spider mites.  Horticultural oils in the diluted form are some of the most useful insecticides for houseplants when you want to control scales, young whiteflies and spider mites.  These oils are highly refined and primarily act by smothering the insects.  Pyrethins are a common ingredient found in many household insecticides. This ingredient is naturally derived from the flowers of the pyrethrum daisy.  They are fast acting, have a very short persistence and are low in toxicity. You will also find insecticides that are derived from synthetic pyrethrins these are known as pyrethroids.  An insecticide for houseplants that is called systemic means it has the ability to be absorbed by the plant.  Those used on houseplants are sold as granules or as stakes.  They are applied to the soil for the roots to absorb. 

If you select to use a pesticide there are cautions you need to follow.  Only use pesticides that are specifically labeled for use on houseplants.  Most yard and outdoor garden pesticides do not allow the use on houseplants.  If possible, take the plant outdoors before spraying to minimize pesticide exposure in your home.  When using aerosol sprays do not apply closer than 18 inches to the plant or injury may occur from the spray.  Avoid treating plants that suffer from environmental stresses such as temperature extremes or drought, this will minimize potential plant injury.  If granules or plant stakes containing DiSyston are used, use extra care when watering.  Excess water can carry this insecticide as it puddles or drips.  This product is extremely toxic.  And finally, ALWAYS READ AND FOLLOW THE INSTRUCTIONS ON THE LABEL!