Fungus Gnats are Back?

Figures.

By Dave Zeldon and Ely Schweyer

Now that we’ve brought our plants inside the house to over-winter, we begin to notice those slender, dark gray flies (0.2- 0.4 cm long) flitting about atop the pot soil. Yuck!

   These insects are known as fungus gnats (Bradysia sp.). Whereas they are considered only to be a minor nuisance in house plants, due to their sheer numbers hovering around an attractive plant, they can certainly take away from its appeal. Below is a bit about these pests and some basic control measures.

How Do Fungus Gnats Affect Your Plant?

Other than their swarming presence, fungus gnats are not a direct threat to your plant, but an indirect threat. As their name implies, they are concerned with snacking on the fungi mycelium living in your plants’ soil. (Yes, it’s there and it’s a good thing!) However, these little flies can transfer disease between plants, making them nuisance pests.

A Quick Look at Their Life Cycle:

Adults may lay 300 eggs at a time, which hatch a week later into tiny, threadlike larvae. The larvae feed upon organic matter in the potting soil. After two weeks, they pupate into winged adults, that have no trouble annoying you to no end.

Basic Control Measures:

• The fastest and easiest method of control is to catch the flying adults with yellow sticky cards. The large cards can be cut into little strips and mounted onto little wooden splints (popsicle sticks) then placed around the base of the plant out of the line of sight.

• Water your potted plant from the bottom (sub-irrigation) by adding water to the saucer it is sitting in. This will keep the soil surface dry, making it uninhabitable for the hatching insect larvae. If the surface soil is already very wet, try placing a few potato discs or slices on the surface of the soil. This will attract the larvae as they migrate to the potato to feed. Simply replace the discs every three to four days with fresh slices to eliminate the next generation of adults.

• If you have a large number of plants afflicted as in a greenhouse situation, an application of predatory nematodes (Steinernema feltiae) as a soil drench is suggested. Nematodes will attack the fungus gnat larvae in the soil which will in turn lead to more nematodes being produced.

Good Bugs Are Working at Eising Greenhouse and Garden Centre!

Here at Eising’s Greenhouse and Garden Centre, we practice what as known as I.P.M. or Integrated Pest Management. Since we try to create a perfect environment for our plants, we also, unintentionally create perfect conditions for their related pests. To keep the pests at bay, we institute series of steps:

1 - Cultural Controls: We select only the healthiest of plant material to sell and keep them healthy through proper fertilization and growing conditions. We’ve learned that insects are attracted to stressed-out plants!

2 - Physical Controls: We are constantly walking through our plant aisles checking for insect and disease presence and removing the affected plants. Also a clean growing area means there is less chance of pest populations building up on alternate host plants such as weeds.

3 - Biological Controls: At the beginning of the growing season, even before there is any evidence of pest problems, we introduce naturally occurring predators into the growing areas. This is to be at the ready for when the pests do arrive!

In our arsenal we have a series of tiny parasitic wasps, microscopic wire-worms called nematodes, predatory mites as well as bacterial inoculants. So therefore, we cannot spray any chemical insecticides as they will hurt our very valuable biological cache!

Did you ever imagine all the behind-the-scenes work that goes into your plant purchases from Eising's to make them the best value around?

For more information – and bug products - visit Eising Greenhouse and Garden Centre soon! 🪰