Are you familiar with twospotted spider mites? What you don’t know could harm or kill your crops.
Twospotted spider mites live on the undersides of leaves, and are oval-shaped insects that are easy to miss—they’re only about 1/50th of an inch long. They sometimes have a brown or orange-red appearance, but are typically green or greenish-yellow in color, and have two dark spots on their abdomens—hence the “twospotted” spider mite.
These critters love to munch on your crops—over 200 species of vegetable and fruit crops, and ornamental plants, to be exact. In fact, scientists at the University of Florida consider the twospotted spider mite to be the most economically significant species of spider mite in Florida—and just about anywhere else in the country.
These spider mites feed on plants by piercing the leaf tissue with needle-like mouths and extracting the contents from plant cells. One twospotted spider mite can destroy 18 to 22 cells in a single minute, and if you’ve got hundreds or thousands of feeding mites, the damage to your plants can hamper photosynthesis. As a result affected leaves may turn gray or yellow. Eventually, your crop may completely lose its leaves and die.
The bugs are found throughout the United States, most often in temperate zones and subtropical regions. They can reproduce very rapidly, especially whenever temperatures are higher than 85 degrees F, humidity is lower than 90 percent, and moisture levels are low—perfect conditions for these insects.
The adult female twospotted spider mite lays her eggs on the undersides of crop leaves, and a single female can produce as many as 20 eggs in one day and several hundred eggs in a lifetime, depending on the temperature and the plant on which she’s feeding. The eggs look like transparent spheres when they’re first deposited, and eventually turn yellowish. After three to 15 days (depending on the temperature) larvae hatch from the eggs and are colorless in appearance with six legs. The larvae undergo two nymphal stages, as a protonymph and then as a deutonymph, and turn pale yellowish to green and develop two more legs for a total of eight. At this point two dark spots become visible on the insects’ abdomens. In as little as five days, with hot and dry weather, the mites will mature into adults and repeat the reproductive process.
