How To Control Lewis Mites During Poinsettia Production
July 16, 2025 Although Lewis mites (Eotetranychus lewisi) used to be more of a cyclical pest, this mite has been consistently bad in poinsettia over the last few years. As regular Lewis mite infestations now seem to be the new normal in poinsettia, it’s time to start thinking about your pest control plan for Lewis mites.
Treatment in Propagation / Early Production:
Given that Lewis mites are difficult to detect but end up causing a lot of damage, the easiest solution is often a single, preventative application of a miticide at the cutting stage.
Unfortunately, products traditionally used for Lewis mites don’t seem to be working as well in the last few years. So, what other options are there?
Avid (abamectin; IRAC 6), although hard on biocontrol agents, is currently our most effective chemical. It can be used effectively without derailing your bio program if you use it early in propagation as a preventative spray, before natural enemies are released. The residues generally dissipate before parasitic wasps are put on at potting. (This strategy obviously will not work if you release bios in propagation.)
Other products that can be used early in the crop (before bract formation) are listed here, but their efficacy may vary, as does their compatibility with biocontrol agents.
Treatment in Late Production:
Controlling Lewis mites later in the crop can be tricky, given that some products are not safe on poinsettia bracts, and can also be hard on parasitic wasps that form the backbone of Bemisia whitefly biocontrol. However, Lewis mites are a relatively slow-moving pest, so you don’t need to blanket the whole bench or compartment. Spot sprays mean you could use harder products like Avid or Kontos and keep effects on natural enemies to a minimum.
If you want to focus on products that are safer for natural enemies, some growers have found Floramite still has some efficacy if followed immediately by Shuttle (acequinocyl). This combination remains fairly soft on parasitoids. Be aware that Floramite and Shuttle are in a similar chemical class (IRAC 20B vs 20D). Therefore, they should be used in the SAME pest generation “window” (two-week period), as opposed to alternating sprays over the season, as this could promote resistance.
If you find yourself needing to do a second spray two weeks after the first spray, then Vendex (fenbutatin oxide; IRAC 12) may be a good option, and is also soft on bios. However, it is NOT safe for use at the pre-bract stage and beyond. Magister (which has no label warnings about bracts) provided about 50% kill of Lewis mites in grower trials last year, so Magister is a potential option to include in a rotation program where biocontrol is a consideration.
Spear T (IRAC 32) is also a relatively new product on the market, derived from spider venom, and is reportedly effective on both two-spotted spider mite and whitefly, and therefore may be useful in poinsettia production. However, close observation would be needed to determine its efficacy on both the Lewis mite and Bemisia whitefly, as well as its effects on parasitic wasps.
As the season progresses, control with contact insecticides will be much more difficult since the canopy is denser. Translaminar or systemic miticides will be more effective for Lewis mites at this time (e.g., Avid, Kontos), but will likely interfere with whitefly biocontrol programs. However, if you’re on a chemical program for Bemisia whitefly (or need to switch to one if whitefly pressure is high), late September or early October is the perfect time to apply Kontos, as it will also help control whitefly nymphs.
For additional information, including collected data and diagrams on the effectiveness of specific biocontrols and pest control products on Lewis mites, please read the original article found on the ONfloriculture website.
Subscribe to eNewsletter
