Neoseiulus californicus–Predatory Mite
Biocontrol Agent Factsheet
Neoseiulus californicus can be used for prevention, control and management of various pest mites and may even help to control thrips. This article focuses on the use of N. californicus outside.
Overview
Pests Targeted: Twospotted spider mite
Pest Stage: Eggs, immatures and adults. Eggs and immatures are best pest life stages to target with predatory mites.
Commercially Available? Yes
Scientific Name: Neoseiulus californicus, Amblyseius californicus (old name)
Biocontrol Agent Type: Predator

Common Names
None
Relative effectiveness
Unlike Phytoseiulus persimilis, a selective and aggressive predator of spider mites, N. californicus can be used for prevention, control and management of various pest mites and may even help to control thrips. It is less effective than the closely related predator Neoseiulus fallacis in cooler climates outdoors because it cannot tolerate cold temperatures and will not overwinter in these regions. However, it is more tolerant of hot temperatures and low humidity present in California and other arid regions. In comparison to more generalist predators (e.g., A. swirskii), N. californicus will be more effective at managing low to moderate pest densities, but less effective in managing high pest densities compared to selective predators such as P. persimilis.
Where to use
Many edible and ornamental crops, inside and outside
Plants with high glandular trichrome density, specifically tomato, are not preferred host plants for N. californicus and will require higher release rates. Tolerates lower humidity and hotter temperatures and is less susceptible to pesticides than other predatory mites. (See ‘How to use’ section)
About Neoseiulus californicus
Neoseiulus californicus was first used commercially against spider mites in 1985. It is now a globally distributed predator used as a biocontrol agent against spider mites (especially twospotted spider mites and other Tetranychus spp.). Researchers are investigating its efficacy against other mites. It is found on various crops and deciduous trees where prey is available. It prefers warm temperatures in sub-tropical climates and can tolerate low humidity. However, it does not overwinter well on outdoor crops in temperate climates. Neoseiulus californicus is considered among the least sensitive predator mite species to insecticides, fungicides and miticides, but can be severely impacted by select products listed below.
- Native/Non-native: Native
- Preferred climate: Arid, humid, temperate, Mediterranean, sub-tropical
- Region: Is effective on outdoor crops in California and the southeastern U.S. or within greenhouses or under tunnels where conditions are warm and dry (but this article focuses on outdoor use).
- Established: yes
- Where established: Globally established in sub-tropical and Mediterranean climates, including California and the southeastern U.S.
Neoseiulus californicus Appearance
Neoseiulus californicus are small, about 0.5 mm long with pear-shaped bodies. They are slightly larger than their prey and lack dense hairs. Eggs are football shaped and have a white opaque appearance. Larvae (immature mites) have 6 legs compared to nymphs and adults that have 8 legs. Larvae, nymphs and adults tend to be shiny and yellow or cream-colored, often with darker yellow or orange markings. Neoseiulus californicus is very similar in appearance to Neoseiulus fallacis.

Neoseiulus californicus, including two adults and a cluster of eggs. Eggs are not usually laid in clusters like this.
Life Cycle
The lifecycle of Neoseiulus californicus when reared on Tetranychus urticae prey at 28°C (82 ° F) and 70% RH. This figure presents the time spent in each developmental stage as demonstrated by El-Laithy and El-Sawi (1998).
How to Use Neoseiulus californicus
Biocontrol category:
- Augmentative—must be released/applied repeatedly
- Conservation—attract and protect from the surrounding environment /node/34440/#conservation
When to use: Neoseiulus californicus performs best in warm temperatures (15-35°C or 59-95° F) and between 65-75% RH during the summer months outdoors. Unlike other predatory mite species, it can tolerate lower humidity levels above 40% RH. Optimal establishment occurs when some prey is available at low densities. Preventative releases of N. californicus can be made before pests are present, but this species will not persist on pollen and non-prey resources.
Where to use: Neoseiulus californicus performs well on indoor and outdoor crops of many plant species where prey is available. Plants with high glandular trichrome density, specifically tomato, are not preferred host plants for N. californicus and will require higher release rates. Neoseiulus californicus prefers warm temperatures, but can tolerate brief periods of cold temperatures (e.g., temperatures falling below freezing overnight). They can tolerate lower humidity levels compared to other predatory mite species. Neoseiulus californicus can feed on a broad range of mite pests and can occasionally feed on thrips and pollen if prey is limited, but are primarily known as a predator of twospotted spider mites and other Tetranychus spp. This species is also less susceptible to pesticides and would be more compatible in IPM programs with spray regimes compared to other predatory mite species.
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. See these instructions on how to monitor for spider mites (YouTube). Neoseiulus californicus performs best if releases are made when spider mite populations are low early in the season. On strawberry, a single release of N. californicus at a 1:10 predator to prey ratio early in the season was able to sustain tolerable twospotted spider mite levels throughout the season. If monitoring cannot be conducted, it is recommended that 1-4 predators are released per plant, or 5,000 – 20,000 per acre depending on infestation levels. For best practice, make releases upwind so predators can aerially disperse downwind to other parts of the field. Multiple releases may be necessary throughout the season, but it is strongly recommended that monitoring is conducted to inform this decision.
Maximizing effectiveness: Neoseiulus californicus is best to use against low to moderate pest densities. If released too early, it may disperse if prey is unavailable and if released too late, it may be unable to provide knockdown of high prey densities. These predators are unlikely to overwinter in cooler climates (with extended periods of below-freezing temperatures), thus yearly applications will be necessary on outdoor crops. Several studies have shown that N. californicus and P. persimilis can be combined into release programs to provide sustainable control of spider mite pests during a season. This compatibility is likely due to their contrasting feeding ecology and development time, but monitoring should be conducted to ensure that both species co-exist where they are released.
Pest stage: Eggs, immatures and adults. Eggs and immatures are best pest life stages to target with predatory mites.
Mode of action: Predator
Conservation: Neoseiulus californicus is found naturally along the coast of California and much of the southeastern U.S. Conservation of this species is possible in these regions. Avoid applying bifenthrin, abamectin and fenpyroximate products and avoid total eradication of available prey for this species to conserve this species. (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.)
Compatibility: Broad-spectrum pesticides can have serious non-target effects on predatory mites, even if they are labeled as selective. In general, insecticides that are less harmful to predatory mites include diamides, Bacillus thuringiensis, diflubenzuron, methoxyfenozide, and pymetrozine and hexythiazox, etoxazole, bifenazate, spiromesifen and cyflumetofen as the most compatible miticides. In comparing predator mite species for pesticide tolerance, several studies have ranked N. californicus among the least sensitive species to pesticides. For N. californicus specifically, the most compatible active ingredient was hexythiazox and the least compatible were bifenthrin, abamectin and fenpyroximate. 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.
See Schmidt-Jeffris 2021 and Bergeron 2020, IOBC-WPRS Pesticide Side Effect Database, Biobest Side Effects App and Koppert - Side effect 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 twospotted spider mite (Tetranychus urticae)
Neoseiulus californicus can feed on a broad range of small invertebrates but prefers spider mite prey, especially twospotted spider mite and closely related species (Tetranychus spp.). Damage by two-spotted spider mites appears as regular chlorotic spots, white-yellow in coloration on the leaf surface. This type of damage is called “stippling”. When populations are large, webbing may be present between leaves. In some fruit-bearing crops, direct feeding on fruit may result in similar damage on the fruit itself, such as “gold fleck” in tomatoes.

Several spider mite individuals and spider mite eggs observed on the underside of bean leaves with magnification.

Example of two-spotted spider mite damage on strawberry leaf, also called “stippling” or chlorotic spotting.
Authors
- 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: January 2022
- 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).
- El-Laithy, A.Y.M., and El-Sawi, S.A. Biology and life table parameters of the predatory mite Neoseiulus californicus fed on different diet. Journal of Plant Diseases and Protection 105, 532 – 537 (1998).
- Escudero, L. A. & Ferragut, F. Life-history of predatory mites Neoseiulus californicus and Phytoseiulus persimilis (Acari: Phytoseiidae) on four spider mite species as prey, with special reference to Tetranychus evansi (Acari: Tetranychidae). Biological Control 32, 378–384 (2005).
- Fraulo, A.B., and Liburd, O.E. Biological control of twospotted spider mite, Tetranychus urticae, with predatory mite, Neoseiulus californicus, in strawberries. Experimental and Applied Acarology 43, 109 – 119 (2007).
- Gotoh, T., Yamaguchi, K. and Mori, K. Effect of temperature on life history of the predatory mite Amblyseius (Neoseiulus) californicus (Acari: Phytoseiidae). Experimental and Applied Acarology 32, 15 – 30 (2004).
- Koller, M., Knapp, M. and Schausberger, P. Direct and indirect adverse effects of tomato on the predatory mite Neoseiulus californicus feeding on the spider mite Tetranychus evansi. Entomologia Experimentalis et Applicata 125, 297 – 305 (2007).
- McMurtry, J. A., Moraes, G. J. De & Sourassou, N. F. Revision of the lifestyles of phytoseiid mites (Acari: Phytoseiidae). Systemic and Applied Acarology 18, 297–320 (2013).
- 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).
- Walzer, A., Castagnoli, M., Simoni, S., Liguori, M., Palevsky, E. and Schausberger, P. Intraspecific variation in humidity susceptibility of the predatory mite Neoseiulus californicus: survival, development and reproduction. Biological Control 41, 42 – 52 (2007).
- Neoseiulus californicus, including two adults and a cluster of eggs. Eggs are not usually laid in clusters like this. Photo by R. Schmidt-Jeffris.
- Several spider mite individuals and spider mite eggs observed on the underside of bean leaves with magnification. Photo by S. Willden.
- Example of two-spotted spider mite damage on strawberry leaf, also called “stippling” or chlorotic spotting. Photo by S. Willden.
Related Links
- (315) 787-2206
- arc55 [at] cornell.edu
- (315) 787-2345
- gme1 [at] cornell.edu