Neoseiulus fallacis–Predatory Mite

Biocontrol Agent Factsheet

Neoseiulus fallacis is a commercially available predatory mite used for prevention and management of mite pests. This article focuses on the use of N. fallacis for biocontrol  outside. This species has also been extensively and effectively used in greenhouse settings.

Common Names

None

Relative effectiveness

Unlike Phytoseiulus persimilis, a selective and aggressive predator of spider mites, N. fallacis can be used for prevention, control and management of various pest mites. It is also more effective than the similar predator Neoseiulus californicus in temperate climates outdoors and can overwinter in northern climates. In comparison to more generalist predators (e.g., N. cucumeris and Amblyseius swirskii), N. fallacis will be more effective at managing low to moderate infestations of mite pests, but less effective than P. persimilis in managing high spider mite infestations.

Where to use

Many ornamental and edible crops, including apple, strawberry, raspberry, watermelon, cucumber, peppers, peppermint, hops and various ornamental. Works best on low-growing plants with denser canopies. Not suitable for tomato.

Outside or inside (although following information focuses on outside use)

About Neoseiulus fallacis

Neoseiulus fallacis is a commercially available predatory mite used for prevention and management of mite pests. It will feed on multiple mite species (including rust mites), but prefers prey of the Tetranychidae family (including twospotted spider mites). It is a valuable biocontrol agent because it can survive on multiple mite pests and is found across much of the US. Neoseiulus fallacis is one of few commercially available predatory mites that can overwinter in temperate climates and provide preventative control in the spring. Neoseiulus fallacis is considered to be among the more sensitive predator mite species to pesticides and would perform best under low-spray regimes. 

  • Native/Non-native: Native
  • Preferred climate: arid, humid, temperate, cold tolerant
  • Region: Nearly worldwide
  • Established: Yes
  • Where established: Established widely across North America.

Neoseiulus fallacis Appearance

Neoseiulus fallacis are small, about 0.5 mm long with pear-shaped bodies. They are slightly larger than their prey, but lack dense hairs and red eyespots. They are tan, cream or orange/yellow in coloration and have a shiny appearance compared to spider mites. As larvae (immature mites), they are semi-transparent with 6 legs. Eggs are oval-shaped, semi-transparent to cream-colored, and slightly larger than spider mite eggs.

Two mites in the foreground, one a Tetranychus urticae adult (on the left) that is being eaten by the other, an adult Neoseiulus fallacis (on the right). Both mites are present against a mottled green leaf surface.

Adult Neoseiulus fallacis (right) feeding on spider mite prey (left).

How to use Neoseiulus fallacis

Biocontrol categories:

When to use: Neoseiulus fallacis performs well in cool to warm temperatures (50-90 F; 10-32 C) and in >70% RH during the spring, summer and fall. These predators can be released for preventative control before pests are identified; however, they are more likely to remain in the crop if some prey is available.

Rate: Most predatory mites are recommended to be released at a 1:10 predator to pest ratio for maintenance of low pest densities, and a 1:5 ratio for control of moderate to high pest densities. Monitoring for prey densities will provide the best estimate for predator release rates. If monitoring cannot be performed, it is recommended that 5 releases of 100 adults (in total, 1000 mites per 1,285 square ft) on 2 m row sections can successfully inoculate a whole field over a growing season for preventative control. For best practice, make releases upwind so predators can aerially disperse downwind to other parts of the field. For control of low, moderate or high prey densities, increase predator density to 1000 per 650, 425 or 300 square feet, respectively.

Maximizing effectiveness: Neoseiulus fallacis is best to use against low-moderate prey densities. If released too early, it may disperse if alternative prey is not present. If released too late, it will likely be unable to provide a quick knockdown of high prey densities. To overwinter predators, ensure that overwintering habitat (i.e., dead leaves and plant debris) is available. Several studies have also ranked N. fallacis to be among the more sensitive predatory mite species to pesticides, thus this species would perform best under low-spray or selective-spray management regimes.

Neoseiulus fallacis performs well on containerized and field grown plants of many species. They can control multiple pest mite species in diverse cropping systems outdoors. Neoseiulus fallacis is sensitive to low humidity below 70% relative humidity (RH). Thus, they are not recommended for release on sparsely canopied plants when RH is low. Performance is generally high on canopied plants, including shrubs and herbaceous perennials, compared to conifers and shade trees. They also perform better on low-growing plants, compared to those that are tall or vertically growing with little canopy. They can be important native biocontrol agents of spider mites in eastern North American tree fruit orchards.

Pest stage: Eggs and immatures are the best pest stages to target, but adults will also be eaten.

Mode of action: Predator

Conservation: Because N. fallacis can be found naturally in most of North America, conservation of this biocontrol agent is possible. Within a growing season, avoid applying broad-spectrum pesticides and avoid total eradication of available prey for this species. It also prefers host plants that create canopies, and tends to disperse from vertical growing plants with little canopy. Canopy plants provide better protection from UV and maintain the higher relative humidity that this species prefers. To conserve predators across growing seasons, ensure that good overwintering habitat (e.g., dead leaves, plant material, tree bark) is available.

Compatibility: Several studies have ranked N. fallacis to be among the more sensitive predatory mite species to pesticides, thus this species would perform best under low-spray or selective-spray management regimes. The most compatible insecticides or miticides for predatory mites generally, including N. fallacis, are diamides, Bacillus thuringiensis, diflubenzuron, methoxyfenozide, pyrometrozine, hexythiazox, etoxazole, spiromesifen and cyflumetofen products. Products to avoid when applying N. fallacis include bifenthrin, abamectin, fenpyroximate, and bifenazate. Bifenazate is surprisingly harmful to N. fallacis compared to other predatory mite species. It is important to note that all products have non-lethal effects on predatory mites that may negatively impact their performance. Products should be used only when necessary to promote biocontrol success.

Neoseiulus fallacis can be used in combination with other predatory mites, including specialist and generalist species against mite pests. However, there is a risk of competitive interference between predator species, especially in greenhouse releases. Monitoring should be conducted to ensure the stability of multiple biocontrol species in the field.

See Schmidt-Jeffris 2021,Bergeron 2020, and the IOBC-WPRS Pesticide Side Effect Database (available through paid subscription) for more details on pesticide compatibility.

Risk: There is no evidence of harm to human or environmental health.

Commercially available: Yes. This species is widely available by multiple distributors.

Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province. 

About pests targeted by Neoseiulus fallacis

Neoseiulus fallacis is a broadly specific predatory mite that prefers to feed on spider mites, but will also consume rust mites. Damage by twospotted spider mites appears as regular chlorotic spots, white-yellow in coloration on the leaf surface. This type of damage is called stippling.

Pest mite species targeted

  • Twospotted spider mite, Tetranychus urticae (Koch)
  • European red mite, Panonychus ulmi (Koch)
  • Cyclamen mite, Phytonemus pallidus (Banks),
  • Apple rust mite, Aculus schlechtendali (Nal.)
  • Banks grass mite, Oligonychus pratensis (Banks)
  • Southern red mite, Oligonychus ilicis (McGregor)
  • Broad mite, Polyphagotarsonemus latus (Banks)
Side profile of a female spider mite. The mite is pale white-yellow, has red eyespots, and two large black spots in the middle of its body that touch.

Twospotted spider mite adult female.

Strawberry leaf with signs of damage by spider mite feeding. The damage appears as regular chlorotic spots, white-yellow in coloration on the leaf surface. This type of damage is called stippling.

Example of two-spotted spider mite damage on strawberry leaf, also called stippling or chlorotic spotting.

Author

Samantha Willden
Cornell AgriTech, Department of Entomology

Rebecca Schmidt-Jeffris
USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, Wapato, WA

Gregory Loeb
Cornell AgriTech, Department of Entomology

Date: October 2021

Modified from Kain, D. and Nyrop, J. March 1995. Predatory Mites. Insect Identification Fact Sheet No. 23. Cooperative Extension, Cornell University, Ithaca, NY.

  • Bergeron, P.E. and Schmidt-Jeffris, R.A. Not all predators are equal: miticide non-target effects and differential selectivity. Pest Management Science 76: 2170-2179 (2020).
  • Coop, L.B. and B.A. Croft. Neoseiulus fallacis: dispersal and biological control of Tetranychus urticae following minimal inoculations into a strawberry field. Experimental & Applied Acarology 19: 31-43. (1995). 
  • Genini, M., Klay, A., Baumgärtner, J. Delucchi, V. and M. Baillod. Comparative studies on the influence of temperature and food on the development of Amblyseius andersoniNeoseiulus fallacisGalendromus longipilus and Typhlodromus pyri (Acari: Phytoseiidae). Entomophaga 36: 139-154. (1991). 
  • McMurtry, J. A., Moraes, G. J. De & Sourassou, N. F. Revision of the lifestyles of phytoseiid mites (Acari: Phytoseiidae). Systematic and Applied Acarology 18: 297-320 (2013).
  • Morris, M.A., Croft, B.A. and Berry, R.E. Overwintering and effects of autumn habitat manipulation and carbofuran on Neoseiulus fallacis and Tetranychus urticae in peppermint. Experimental & Applied Acarology 20: 249-257 (1996). 
  • Navajas, M. Host plant associations in the spider mite Tetranychus urticae (Acari: Tetranychidae): Insights from molecular phylogeography. Experimental and Applied Acarology 22: 201-214 (1998).
  • Knapp, M., van Houten, Y., van Baal, E. & Groot, T. Use of predatory mites in commercial biocontrol: current status and future prospects. Acarologia 58: 72-82 (2018).
  • Schmidt-Jeffris, R. A., Beers, E. H. & Sater, C. Meta-analysis and review of pesticide non-target effects on phytoseiids, key biological control agents. Pest Management Science 77: 4848-4862 (2021).
  • Adult Neoseiulus fallacis (right) feeding on spider mite prey (left).
  • Neoseiulus fallacis development time and lifecycle at 20°C within growth chambers. The data are from Genini et al. 1991, and the artwork is by S. Willden.
  • Twospotted spider mite adult female. Image credit: R. Schmidt-Jeffris.
  • Example of two-spotted spider mite damage on strawberry leaf, also called stippling or chlorotic spotting. Photo by S. Willden.