A microscopic mite about .01 inch long is giving nurseries fits because it is destructive, yet difficult to detect, the Capital Press reported. According to Robin Rosetta of the OSU Extension Service, the eriophyid mite, also known as the gall mite, can cause galls, scarring, discoloration, wrinkling and malformation on growing shoots. The tiny bugs are usually not noticed unless one looks under a magnifier or loupe. The mites come in a large number of different varieties, each specializing in a different type of plant. It is believed that the bugs become active in the spring just as warm weather pushes plants out of dormancy. Researchers are concerned that nurseries unwittingly may be helping the mite spread through the propagation process; when they checked several nurseries, they found infestations in all the scion blocks. But that may also be the key to shutting the mites down.