Spider mites are very small–in fact, nearly too small to be seen without magnification. Despite their small size, however, the impact of spider mites on the plants that they colonize is huge. They are not insects but arachnids, and like their close relatives, spiders, spider mites also spin webs. These webs are one of the important warning signs that plants are suffering an infestation of spider mites, and they can themselves harm plants by collecting dust, mold/mildew spores, and other contaminants. Spider mites are extremely common on plants of all types, but in most cases they go unnoticed. In cannabis crops, however, they tend to concentrate and inflict heavy losses.
The primary damage inflicted by spider mites on cannabis crops, however, is direct feeding on leaves. When thousands or millions of mites attack the leaves, they wither and die, potentially destroying a cannabis harvest. If left untreated, spider mites multiply very quickly, exponentially increasing the damage done to the plants.
Like many of the pests and fungi that plague cannabis grow rooms, spider mites thrive in warm conditions. This means that young cannabis crops are very attractive to mites, which are small and light enough to float through the air until they land in a favorable feeding and breeding environment. This means that growers must always be vigilant and take measures to prevent the colonization of their crops by invading spider mites.