The taxus bud mite is a species of eriophyid mite that is sometimes a significant pest of yew (Taxus spp.). It is common in several Northeastern states, and widely distributed throughout Europe. Despite the eriophyid mite being described over a century ago, very little is known about the specifics of its biology and life cycle. The mites pass through an egg, larva, nymph, and adult life stage. Taxus bud mites crawl between host plant bud scales, the location where they overwinter. By late summer and fall, feeding and reproduction of the mites occurs. As many as 1,000 individual taxus bud mites may live in a single bud. As new buds are formed in the summer, taxus bud mites migrate to them to begin their life cycle anew (Johnson and Lyon, 1991). In British Columbia, Canada, mites colonize both vegetative and reproductive buds and peak in their activity from May to August with lowest numbers in March and October. The height of taxus bud mite activity in that study was observed in June (Marshall and Clayton, 2004). Taxus bud mite showed preference for terminal and lateral buds on Pacific yew compared to reproductive, axillary, or latent buds. In British Columbia it is hypothesized that the taxus bud mite was introduced to Pacific yew from English yew (T. baccata) (Mitchell et al., 1997). Magnification is required to observe the taxus bud mites themselves. According to Marshall and Clayton (2004): "using a dissecting microscope, larvae of C. psilaspis can be identified by their small size (average length 96 µm) and translucent or white coloring; nymphs by their larger size (average length 130 µm) and white, or translucent with orange-blotch, coloring; and adults by their larger size and orange–brown coloring".
Twigs and buds of the host plant are impacted. The taxus bud mite causes deformed buds and needles on its hosts. Attacked buds may sometimes perish following enlargement and "blasting" (wither and fall or abort from an otherwise healthy plant). Secondary microorganisms can cause decay of the damaged buds. Heavily infested buds will not grow in the spring. Lighter infestations may result in distorted needles and shoots.
Monitor buds visually for signs of swelling or decay. Infested host plants may also have distorted needles or shoots. Magnification is required to observe the mites or their eggs.
Infested branches may be pruned out and destroyed.
Temperature and predation are assumed to be significant factors in population fluctuation of the taxus bud mite. It is hypothesized that taxus bud mite abundance increases following favorable spring temperatures and availability of new food resources, whereas predation by other mite species and lower temperatures, which prolong development, may cause the low population numbers of bud mites in March and October (Marshall and Clayton, 2004). Potential natural enemies of the taxus bud mite include but are not limited to: phytoseiid mites, Epitrimerus gemmicola, and Pentamerismus taxi (Marshall and Clayton, 2004).
Abamectin (NL)
Carbaryl (L)
Horticultural Oil (L)
Pyrethrins (L)
Pyrethrin + piperonyl butoxide (L)
Spiromesifen (L)
Active ingredients that may be applied systemically include: abamectin (injection) and neem oil (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
