Pine needle distortion due to Trisetacus ehmanni.
Photo by C. Swift.

Needle distortion resembles herbicide damage
Photo by B. Hammon

Close-up showing Trisetacus ehmanni feeding on a ponderosa pine needle.
These were feeding under the sheath of the fascicle.

They are .2 to .3 millimeters (0.078 to 0.118 inch) in length.
Photomicrographs by B. Hammon.

Tricetacus ehmanni feed under the sheath of the fascicle at the base of the needles. They can kill buds and cause yellowing, distortion and death of needles.

General Information about Eriophyid Mites:

"Eriophyid mites are extremely tiny (less than 0.3 mm in length), microscopic worm or spindle-shaped mites with elongated bodies. They resemble cigars with the head and legs located on one end of the body. They have two body regions: mouthparts (Gnathosoma) and the remainder of the body (Idiosoma). The idisoma is similar to the abdomen of insects. Eriophyid mites only have 2 pairs of legs, which is a unique characteristic among mites (all other mites have 4 pairs of legs). They cannot be detected with the unaided eye.

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. At the tip of the idisoma is a sucker, which allows the mite to hold on to the plant surface. 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. Feeding generally results in densely packed or distorted growth to both the flowers and foliage that appears "rough" looking. However, eriophyid mite feeding can result in a variety of symptoms including galling, clustering or "witches broom," swollen or thickened growth, leaf blistering, and russetting or bronzing of leaves. Eriophyid mites are also the only group of mites known to transmit plant viruses.

Eriophyid mites tend to live together in large numbers and reproduce within the folds of plant tissues. With the aid of a dissecting microscope (set at 100X) the mites and eggs can be seen. 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. The reproductive potential of eriophyid mites is very similar to two spotted spider mite. Each female mite may lay up to 100 eggs. Several generations may occur throughout the growing season.." - Cloyd, R.W.

Control:

Dr. Whitney Cranshaw suggests Forbid (spiromesofin) -click for the Forbid label, or Floramite (bifenazate) -click for the Floramite label, but did state there is no data to support their efficacy on eriophyids. Both of those materials are good on immature spider mites. Adding a surfactant will help move the active ingredient under the sheath of the fascicle where the mites reside.

Carbaryl is effective on eriophyids - click for the Carbaryl label. However, if spider mites are also present carbaryl should be avoided due to its effect on predators of spider mites. Carbaryl is known to increase spider mite populations.

Tank mixing carbaryl and a miticide is an option when both eriophyid mites and spider mites exist on the same plant. Check the compatibility of the materials used. See http://pmep.cce.cornell.edu/facts-slides-self/facts/gen-peapp-compat.html for further information on compatibility.

Reference:

http://floriculture.osu.edu/archive/oct05/Mite.html - Eriophyid Mites, By Dr. Raymond Cloyd, Associate Professor
Department of Natural Resources and Environmental Sciences University of Illinois