What are Spider Mites?
If your plants have stopped thriving, you may think that low water levels or poor soil balances may be the cause. However, certain bugs may be to blame. Aphids and weevils are notorious agricultural pests. However, spider mites are also commonly encountered around homes and gardens.
Spider mites are arachnids, meaning they are related to spiders, ticks and scorpions, rather than insects. Spider mites belong to the family Tetranychidae. Some of these species spin silk and form webs, mostly to protect their eggs and young from predators.
Spider mites grow from egg to adult over the course of five stages. Some female spider mites have an average lifespan of 30 days and can produce 100 eggs on average during that time. In the case of the twospotted spider mite, the young can complete their development in as few as five days, meaning that a new generation is now ready to reproduce. For this reason, twospotted spider mite populations tend to explode, especially under favorable climatic conditions (hot and dry). Sizable populations of twospotted spider mites are also more likely to coat plant leaves and stems with webbing.
There are many different species of spider mites, and, while they do come in a variety of colors, it is often difficult to identify them with the naked eye. Spider mites are virtually microscopic — adults average 1/50 of an inch in length, which is about as large as the size of the period at the end of this sentence.
How to Identify Spider Mites
If you notice stippling or webbing on your plants, use a magnifying glass to check both sides of its leaves. If you are still unsure if you have a spider mite problem, take a sheet of white paper and turn a leaf over on top of it. Tap it gently. Wait and watch for movement — if spider mites have infested the plant, you should be able to see them moving across the surface of the blank paper.
What Damage Can Spider Mites Cause?
Spider mites feed on the chlorophyll in plants. They use their piercing mouthparts to puncture individual plant cell walls and suck out the vital fluids those cells contain. Leaves bearing many tiny white spots or showing a stippled appearance are a likely sign of a spider mite infestation. If spider mites are allowed to continue feeding unabated, these damaged leaves will likely turn brown and eventually drop off the plant. Plants that are over-fertilized may be more attractive for female twospotted spider mites as they contain more proteins and amino acids which are a food source for this pest.
Twospotted spider mites may also feed on grass, soybeans, corn and fruit trees, among other crops and plants.
There are other plant feeders that can cause damage similar to spider mites. That’s one reason why it’s important to contact a trained professional if you spot what looks like spider mite damage.
How to Help Prevent Spider Mites
Preventative maintenance is the best strategy. Check your landscape plants every one to two weeks for signs of spider mites. Because indoor temperatures are stable and climates tend to be drier indoors, house plants should be checked weekly. Spider mites are particularly fond of fruit trees, vegetables and popular ornamentals, such as roses.
When watering your plants, also clean them. Use a high-pressure hose and spray plant leaves weekly. Be sure to adjust the water pressure so that it will still be safe for your plants, though. Also be sure to spray the underside of the leaves, as spider mites are most likely to congregate there.
Finally, if you are purchasing new plants, be sure to inspect them for signs of spider mite damage. Spider mites that you unsuspectingly import to your garden or home can rapidly colonize either — or both.