The recent cold weather has forced all of us to bring our houseplants inside and many times when the house plants come inside so do the problems. My wife has already had a problem on her African violets with citrus mealy bug insects and I’m sure there will be some other aphids appear on the other porch plants that are now houseplants. Anytime we put plants outside for the warm months they do very well but they also have an opportunity to pick up many insect problems. Outside predators, beneficial diseases, and cultural practices like a good rain or water shower do a good job keeping the harmful bugs from being a problem. Once inside though these pests can grow and multiply quickly in a warm environment free from disturbance. Here is a list of major house plant insects and signs of damage to look for.
Aphids are tiny soft bodied insects that are from lime green to yellow in color. They suck the plant juices through a piercing sucking mouthpart. The damage will show up as yellow, discolored leaves and you can usually find the insects on the new growth. Taking the plant outdoors on a warm day and spraying with strong blasts of water works well or you can use a spray of water and vinegar on a regular basis. A pyrethrin based insecticide is the safest chemical control.
Mites are a particularly bad problem if you get them. These very tiny insects on the undersides of leaves will suck out the chlorophyll leaving white spots on the leaf surface. They are hard to control, but strong water sprays on a regular basis do help. I use products containing Neem but check labels for the mention of spider mites before purchasing an insecticide.
Snails and slugs love house plants because we usually keep the soil so moist and the pot full of dead leaves. You can know if you have problems by the characteristic silvery streaks left on leaves from their travels. The best method of control is hand picking them off. You can buy a prepared slug bait or use diatomaceous earth or even beer in a lid. They’re heavy drinkers!
Mealybugs are beautiful insects, unfortunately they are harmful. Mealybugs look like very tiny balls of cotton. They move very slowly and suck out plant juices at the stems and leaf bases which cause wilting. Mealybugs can be dabbed with a Q-tip dipped in alcohol or sprayed with citrus oil, or neem oil. Diatomaceous earth can be spread on the leaf and stem surface.
Scale insects can be seen as small bumps on the surface of the stem. They really look natural until sufficient numbers are reached so that you notice them. The first stage of scale insects is called crawlers when they hatch from the egg. These crawlers move along the stem until they locate a good location to feed and then begin to secrete wax in tufts around their body. These waxy tufts form the “scale appearance” that resembles the bump on a stem. Scale is somewhat hard to control because this wax forms a fairly good barrier to other insect predators and to some insecticides. Using an oil based spray like citrus oil will smother the scale giving good control. Be careful anytime you use an oil based spray because they can be harmful to the plant if the oil is too heavy.
Have you seen small gnats flying in the house because this can be a common problem with house plants? Fungus gnats are small flies that are blackish with long legs. Since they're flies, they only have two wings. The larvae are maggot-like and live in the soil of potted plants and they are the real problem since they eat plant roots. Overwatering may be the main problem and a simple way to get rid of the gnats is to reduce the water supplied to the plant by only watering the plant when the soil is dry. Reducing the water supply will get rid of the larvae so will eventually reduce the adult gnats seen flying around. There is no good way to get rid of the adults that are already present.
One last house plant problem is not insect related at all. Remember that heaters do a great job protecting from the cold but they also dry out the air. Keeping house plants away from vents and also spraying with water occasionally will keep them much healthier. Another trick is to buy a spray form of anti-transparent to keep the leaf from releasing too much moisture in the dry winter time.
My Web Page
- Bob Whitney
- As an Agriculture Extension Agent for Texas AgriLife Extension Service I have had an opportunity to be involved in just about every aspect of agriculture. From the 5,000 cow dairy to the types of trees to use in a home landscape I have had a chance to learn how the different parts of an agriculture systems work together. Seedless watermelons, drip irrigation, pecan orchard management, fruit crop development, dairy nutrient management, environmental issues confronting agriculture, producer tours, field days, research projects and more have been a part of my life for over 30 years as I lived and breathed agriculture. Since 2004 I have been actively involved in consulting internationally working in Honduras, Guatemala, Egypt, Jordan, Iraq, India, and China. I have worked with missionaries and other groups dedicated to alleviating poverty among third world farmers. I lived in the Middle East in 2007-2008 working on a project for the Borlaug Institute of International Agriculture at Texas A&M University. In this project I was the Chief of Party and Team Leader for a $5.7 Million dollar effort to train Iraqi Extension agents and specialists in all aspects of agriculture.