Are your plants off-color, fading, yellowing, or losing vigor? You may have a mite problem!
There are several species of mites that affect plants. They are often known as red spiders, red mites, or spinning mites. They may be red, brown, green, or yellow. Mites appear to be round, are barely visible to the naked eye, and have 8 legs when fully grown. When viewed with a magnifying glass, they appear sparsely clothed with long, rigid hairs. In cases of heavy infestations, they may spin a protective web over the surface of the foliage where they are feeding.
Plants Attacked
Mites affect a wide variety of plants in the yard and garden. The spruce spider mite, for example, not only feeds on various species of spruce, but will also feed on the needles of plants such as arborvitae, juniper, larch, pine, and hemlock.
Damage
Mites damage plants by sucking juice or sap from the foliage.
Appearance of Damage
Light infestations usually go unnoticed. Heavy infested plants take on a speckled, yellowish appearance and lack the rich green color. In many cases, the leaves will drop off after the characteristic fading or yellowing. With evergreens, the older needles may be attacked first and injury is noticed on the lower and inner parts of the tree. Injury is then noticed toward the top of the tree as the season progresses. Badly infected plants will usually have a fine cobwebby appearance on the leaves or needles.
Development
Mites may pass the winter as adults or eggs, depending on the species. After mating, females begin laying eggs. The eggs are tiny, spherical, shiny, and very small. Eggs hatch in 4 or 5 days. The young look similar to the adults, except they are smaller and have only 3 pair of legs. As the mites grow, they shed their skins; this is called molting. After molting, the young all have 4 pair of legs. They molt 3 times before becoming adults. Generations overlap and all stages (egg to adult) can be found on most plants during the summer months.
Checking for Mites
If plant foliage begins to take on an off-green color and mites are suspected, one way to determine if they are present is to make a foliage check. To do this, take a white piece of paper, hold it under a branch suspected of having mites, strike the branch hard against the paper. This should dislodge the mites and even though they are only 1/50 of an inch long, you should be able to see the oval mites against the white background. Do this 3 or 4 times, making sure not to miss the presence of mites.
