Eriophyid mites can cause distortions in flowers and other plant parts. The following is information on this pest of greenhouses and nurseries.
Eriophyid mites are extremely tiny (0.3 mm in length), microscopic, spindle-shaped mites with elongated bodies. They resemble sausages with the head and legs located on one end of the body. Eriophyid mites only have 4 legs, which is a unique characteristic among mites. All other mites have 8 legs as adults.
These mites are a specialized group of plant feeders. In general, many eriophyid mites feed on a few closely related species or genera of plants. Eriophyid mites feed deep within the plant tissues sucking out plant juices with their stylet-like mouthparts and transferring a substance, which causes deformation of plant growth. Eriophyid mites live and reproduce within the folds of plant tissues. The eggs are spherical and generally laid in groups. They hatch in less than two weeks into young mites that may take approximately two weeks to a month to mature into adults. Several generations may occur throughout the growing season.
Eriophyid mites can easily come in on plant material from a supplier. If you are a grower examine your plants for eriophyid mites in September and make sure you are not selling customers infested plants. Once damage is evident, it is too late because the mites are already established within the plant. The number of miticides for controlling eriophyid mites is limited. Pest control materials with translaminar properties are your best choices for "managing" eriophyid mites. These would include abamectin (Avid) and chlorfenapyr (Pylon) which can be used in greenhouses only. Additional pest control materials that may work on eriophyid mites, if you can make contact, are pyridaben (Sanmite), fenpyroximate (Akari), and endosulfan (Thiodan).
Reprinted in part from the September 4, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center http://www.ipmnet.umd.edu/09Sep04G.pdf