Gnats

Q. I have 2 very large house plants. One is a rubber tree and I am not sure what the name of the other plant is. They are both infested with gnats. I have replaced the top soil on the rubber tree and sprayed them with house plant insect killer, but they are still there. Any other suggestions?

A. The reason the fungus gnats are still there is that you are not breaking the life cycle. If you spray the adults that you see once or maybe twice, you will kill them. You will not be rid of the adults which you did not hit nor the eggs and larval stages.

I want you to go to your local garden center or nursery and buy a systemic insecticide whose label mentions gnats. Ask an assistant if you cannot find one, but it is a general one used commonly for ants of various types. It is easy to use.

Read the instructions carefully and follow them closely. I want you to apply once a week for three weeks. It will be mixed in a watering can and applied as a drench right into the soil. Do not apply when the plants are dry as you may burn the roots. Allow mixture to drain out the bottom holes into a saucer and empty one hour later. Do not fertilize during this treatment period.

The eggs are laid in the top soil. Clearing out and replacing the top inch of soil before treatment will help too, in addition to the drenching. Once the eggs and larvae are killed, there will be no more adults.

Keep in mind that they are a nuisance and really do very little harm to your plants. Also, if you can find the yellow sticky pads or pest strips, place one by each plant. The color attracts the adults and they stick to it and die.

Q. How can I get rid of gnats in the dirt of house plants?

A. These fungus gnats are a bother and ugly flying around, but they do little damage to your plants. Since they eat fungus, you need to go buy a fungicide for house plants. Check names like Scotts, Hyponex and Ortho. Be sure to follow the directions very carefully and repeat as called for.

You can also help the situation by watering the plant less, thus keeping the soil surface drier, so that they will not have the fungus present, which needs moist environs to grow.

Move the plant closer to the sunlight, and that will cut down on fungus. They do not like growing in a lot of light, preferring the shade.

All these procedures will help. Best of luck...I have them around my African violets often, and have put out those Shell no-pest strips [the yellow kind]. They are attracted to the color and then stick to the glue and die. Try hanging a few of them around where they are seen flying.

Q. I have a variety of trees and exotic plants indoors and seem to have accumulated a large gathering of gnats. How do I get rid of them?

A. There are three methods I will recommend:

Spray. Go to your nearby garden center or nursery and check out the insecticides for gnats, flies, flying insects. Even Raid House and Garden spray works well for me. Do not leave any sitting water around, not any rotting fruit or plant material as these dry them to the area for food. They are not eating your plants, but decaying organic material. Some do lay eggs in the soil so larvae hatch out and can chomp on the roots.

Systemic. You can sprinkle it right on the soil surface and stir it down maybe 1/2 inch. It dissolves in the moisture from watering and humidity. The insects will die from it if ingested while eating, or even resting on it, as their feet will get poisoned. It is applied only once every 4-6 weeks. Read the label directions well.

Yellow pest strips, as Shell. Hang them wherever you are seeing the insects. The color draws them to the cards and the stickiness causes them to become trapped and die. I keep mine hanging year-round and change when they are getting dirty. You will be amazed at how many are trapped in this fashion! Also works well for blossom thrips [if you have spilled pollen, you have thrips, probably!]

Suzy writes~
I love having house plants but am recently finding gnats bedding in my plants. What can I use to rid of them?

Gnats are not harmful to your house plants. They are more of a bother, feeding off the decaying organic material on top of your soil mix, but not the plant stems or roots. Cut down their population [but not a total elimination] by allowing all plants to dry enough that the top soil feels dry to your finger touch before applying more water. Do not wait so long as to cause wilting but the drying of the top mix material will cut down on egg production and hatching, thus there will be a small population. Also, spray lightly once every two weeks with a general house plant spay as Ortho, Raid, Schultz's or Miracle Gro, whatever is locally available. Aim spray directly onto soil surface. It is not necessary or beneficial to spray the foliage.