CUISINE & CULTURE
Outdoor temperatures are below freezing right now, but indoors temperatures are comfortable for humans and houseplants but also plant pests.
The most common houseplant pest is that small, black, fly-like insect, the annoying fungus gnat.
There are four developmental stages in the life cycle of a fungus gnat: egg, larva, pupa and adult. Eggs can be brought indoors in used potting media. Eggs are tiny, opaque and shiny that may be found in groups or as individual eggs on the surface of the media. Larvae appear after the egg stage.
The larvae are the harmful critters as they feed on moist organic matter. Larvae are also small, about .25 inch, opaque with a shiny black head. Larvae habitate potting media or can be found inside feeding on plant tissues under the surface. Plants that harbor a heavy infestation will have yellowing foliage and overall poor growth.
The pupal stage follows the larval feeding stage. Larvae pupate in plant debris or organic matter in the potting soil and adult flies that are similar to a fruit fly emerge from the pupae.
It is at the adult stage that gnats become bothersome as they flit about. Fungus gnats are poor fliers and do not fly far from the infested pot.
Larvae and eggs flourish in moist or overwatered potting soil. The easiest remedy to avoid an infestation is to not overwater the potting media. Since potting media does not dry out as quickly indoors as it does when outdoors, sidestep infestations by watering only when media is dry to the touch. Avoid reusing potting media that has held other plants and heavy with peat moss.
If fungus gnats are already present, decrease watering, place a layer of clean sand on top of the dry media. For a biological remedy place a cup of vinegar on top of the soil or nearby since gnats are attracted to the odor. Another anecdotal remedy is to place a hunk of sliced potato on the media surface as it is said to attract the larvae of the fungus gnat.
Another pest that is not unusual on houseplants are the mealy bug. These sessile, cottony insects suck phloem (sugary) sap, resulting in yellowing foliage. Kill them one by one by removing them with a cotton swab soaked with alcohol.
In next week’s column will be more on winter care of houseplants.
Ellen Peffley Harp, a retired professor of horticulture at Texas Tech University, writes about gardening for several Texas newspapers.
