Tetranychus urticae, or the “two spotted-spider mite,” as it is more commonly known, is the most common spider mite found in potted house plants. This species is probably native to Europe, and it is most abundant in the northern half of the US, but they can also be found in subtropical states. In Massachusetts, the two-spotted spider mite is a serious arachnid pest of cultivated plants both outdoors and indoors, and their excessively small size makes them very difficult to see without the aid of a magnifying glass. Spider mites are particularly common indoor pests in the winter due to their preference for warm and dry conditions, and even during Massachusetts summers, the outdoor climate is often too humid for the pests. Also, spider mite infestations often start after residents bring potted plants into their homes before the winter season. The two-spotted spider mite has an oval body and their color varies between different shades of yellow, red and green. As far as insect pests of houseplants go, spider mite infestations are relatively challenging to eliminate.

Spider mites spend most of their time on the undersides of leaves, but when their populations are abundant, they can be found on other parts of potted plants. Heavy spider mite infestations see the pests construct silk webs between adjacent leaves, and in some cases, these webs are found covering entire plants within homes. Despite their tiny size, two-spotted spider mites can often be seen crawling on this webbing, as their bold colors contrast sharply with the white silk. Spider mites use their mouthparts to extract plant juices, which removed chlorophyll. As a result of chlorophyll loss, white or yellowish speckled dots appear on the surface of leaves, eventually causing leaves to develop a bronze discoloration. Continued feeding can cause defoliation, stunted plant growth, and even plant death. Pest control professionals can eliminate spider mite infestations by spraying conservative amounts of environmentally friendly chemical solutions on the undersides of leaves.

Have you ever discovered damage to your houseplants that you later learned resulted from a spider mite infestation?