Hill Gardens of Maine - Here Come The Gnats & Mites!

Click on "Teddy" for Fred's Amazing Journey Back In Time

Answers to your gardening questions

Five-part article series on flower-drying starts here

Eight-part article series on vegetable gardening starts here

Asian Lily Beetles

A new scourge in New England ornamental and veggie gardens.

Japanese Beetles

They can be controlled...but not the way you think.

An effective Deer Fence!

Only three feet tall...and no deer has ever jumped over it!

Here Come 'da Gnats & Mites!
by Fred Davis, MG, Hill Gardens of Maine (To view other previous articles, click Archives)

Welcome through Fred's Garden Gate! Now that our seeds are up and beginning to stretch for the ceiling, we have another two problems to contend with – both so very tiny, yet so very pesky. Animal predators seek out and hunt down weaklings and the young; insects seem to follow a similar pattern. A plant in a stressful and hostile environment can quickly fall victim to tiny creatures bent upon their destruction.

Fungus Gnats: Instead of thriving in droughty conditions, these winged little monsters proliferate in the algae slime on soil surfaces resulting from over-watering. Lycoriella mali look like pygmy mosquitoes and usually end up staring you straight in the eye while you’re reading or eating breakfast. Adults devote their entire week-long life to locating a mate and producing about 200 eggs. Laid in the wet slime on overly-wet soil, they hatch in about four days, burrow down and begin eating fine roots and other organic matter. (I'll get a photo of fungus gnats in here as quick as I can!)

Yellow sticky traps – available in garden stores – hung every few feet just above containers of plants will trap adults, hopefully before they have a chance intimate liaison with a mate. A soil drench using Safer’s Insecticidal soap works well but can smell ‘musty’. BT (Bacillus thuringiensis) applied liberally onto moist soil is highly effective and completely natural. Bacteria in this preparation invade the insect larvae’s digestive tract, cause perforations, and ultimate death.

Best of all is prevention. Don’t bring a stressed-out, algae-covered, potted plant into your house. Equally important, avoid over-compensating for desert-like conditions in your heated home by over-watering. Throw wet and wilted plants out (all the way out) and repot those with algae growing on soil surfaces.

Now for a particularly difficult rascal to deal with: the especially distressing little creature – Two-spotted Red Spider Mites (Tetranychus urticae). This one is not actually an insect, per se, but rather a true spider which prefers reduced humidity. They are very tiny, and hoards of them may be present, usually feeding at the tip-ends, on flower buds and on the undersides of leaves. A sure sign of mites is the presence of very fine and closely-woven webs, easily visible in bright light. Another indication is the presence of ‘grit’ on the undersides of leaves or on the table beneath the plant.

They’re apt to spread rapidly since they cling to clothing, hands and snips. Occasionally, ‘recycled’ potting soil and unwashed containers are also a factor in their spread.

A number of control measures offer some relief. Since Spider mites prefer dry and hot conditions, increasing humidity and lowering temperature are important factors. Increased moisture can also stimulate an otherwise harmless disease which attacks mites. . . but that, on the other hand, can set up perfect conditions for fungus gnats. What a world!

Closely inspect every plant brought into your home, greenhouse or garden, and reject any which have very fine ‘spider webs’ among the leaves, terminal buds or flowers, and keep a critical eye on plants already in residence. A good, stiff water spray will usually knock adults off and destroy their webs. That, combined with temperature and humidity control and a thorough drenching with Safer’s Soap should take care of them. Apply Safer’s every four or five days until all signs of mites abate. Above all, be thorough! Give plants a good drenching. . . including the undersides of leaves.

It wouldn’t hurt to wipe down the shelf or tabletop with something strong like Pledge or other polish once in a while. If the smell doesn’t get ‘em, the oils will. Don’t forget to wash your hands and indoor gardening tools and be conscious of where your shirt sleeve has been.

Got your peas in yet?

Our Local Weather

Find your State and County Cooperative Extension Office

Which Maine Hardiness Zone Do I Live In? (.pdf)