JoAnne Skelly: Whirligig mite has benefits

I have often written that I find the world of insects and arachnids fascinating. This comes from the person who as a child was terrified of spiders. However, my fear disappeared and my appreciation grew once I starting studying them. I thought I would finish out the year discussing a new critter, well new to me anyway.

Last week at The Greenhouse Project, Cory King, the greenhouse manager and educator, showed me a bright orange spider-like creature and wondered if it was a mite. I’m used to mites being so tiny you need a magnifying glass or a stereoscope to see them. This persimmon-colored 8-legged animal was certainly big enough to see without help. This week Cory told me he had researched it and found it was a whirligig mite, scientific name — Anystis baccarum.

The whirligig mite’s common name comes from the mite’s rapid whirling movement, similar to that of a top or pinwheel. It is a generalist predatory mite. This means it will eat anything small enough for it to catch, including insect pests such as aphids, leafhoppers and thrips as well as arachnid pests such as spider mites. It pierces its prey with its mouthparts and then sucks out the bodily juices. Researchers in Ireland and England are exploring if this mite can be used as a bio-control, particularly in orchard pest control programs, to reduce orchardists’ dependence on chemical pesticides that kill pest and beneficial insects and arachnids alike.

This mite species has no males and eggs reproduce without fertilization (parthenogenesis), developing on the female’s body. After hatching, it takes about one month for a mite to grow to adult form. Then, the adult only lives for 15 to 17 days. It can grow to approximately 1/16 of an inch in diameter (1.5 mm).

We have been having quite a problem with leafhoppers in the greenhouse, which we operate following organic pest control and fertilization practices. They are hard to control because they hop away before you can swat, spray or dust them. I’m glad Cory identified this mite as a beneficial or we might have killed it. He and I are both hoping that our little orange friend will hatch some eggs and the new generation will feed on the pests in the greenhouse, especially leafhoppers.

The lesson we learned is to identify any new insects or arachnids we find before we implement a pest management strategy. We always want to save and encourage the beneficials.

JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at


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