Neoseiulus californicus
A pale, pear-shaped predatory mite of about 0.4–0.5 mm that feeds mainly on spider mites but also takes broad and cyclamen mites and thrips, and can live on pollen when prey is short. It is slower than Phytoseiulus persimilis, but it survives longer without spider mites and copes better with heat and dry air — so it is the one to release early, while mite numbers are still low, and to keep going through warm spells.
At a glance
- Mode
- Selective predator — larvae, nymphs, adults
- Rate
- 5–125 /m² per release by supplier; 100–200 /m² on hot spots (Biobest)
- Ships as
- Mites in vermiculite, or breeding sachets
- Temp
- Best 13–32 °C (Koppert) or 15–35 °C (Cornell); releases from 10 °C (Biobest), active from 8 °C (UConn)
- Humidity
- Prefers above 60–70% RH; tolerates about 40%
- Setting
- Greenhouse, indoor, soft fruit, outdoor crops
How it works
It pierces its prey and sucks it out. Every stage feeds, including the larva, which the larva of Phytoseiulus does not, and it prefers spider mite eggs, larvae and nymphs to adults. Biobest puts its daily intake at about five adult or nymph spider mites and ten eggs or larvae; females lay about two eggs a day and live around three weeks in warm conditions (UC IPM). At 30 °C it completes its life cycle in about four days.
Koppert says it prefers spider mites but can also feed and survive on other mites, thrips and pollen. That is the trade: it is slower-acting than Phytoseiulus, but it can hold on in a crop when spider mites are scarce, and Cornell says it tolerates humidity down to about 40%. Cornell also notes it will not persist on pollen alone and is unlikely to overwinter outdoors where there are long spells below freezing. Released early, at low mite numbers, it keeps them down; against heavier infestations suppliers pair it with Phytoseiulus persimilis on the hot spots.
Is it established?
It is small and pale, and Koppert notes it cannot be told from similar predatory mites by eye — so judge it by what happens to the spider mites. Check leaf undersides with a 10× lens.
- DAY 1Pale, shiny, pear-shaped mites moving on the leaves where you released
- WEEK 1Oval, translucent predator eggs, larger than the round spider mite eggs, on leaf undersides
- WEEKS 2–4Spider mite counts level off or fall on the indicator plants you tagged
- WEEKS 4–6Sachets empty; hang new ones if spider mites are still being found
Release & handling
Loose mites come in a vermiculite carrier; breeding sachets hold about 100 mites plus bran and food mites, and release roughly a thousand over four to six weeks (Biobest). Use both on arrival. Koppert allows one to two days at 8–10 °C in the dark; Biobest stores sachets warmer, at 15 °C. Arbico says not to refrigerate and to use within 18 hours.
Use the same day
If you must wait: bottles cool (8–10 °C), dark and lying flat; sachets at about 15 °C.
Onto the leaves
Turn the bottle gently to mix, then sprinkle onto horizontal leaves. Leave the bottle in the crop so stragglers can walk out.
Hang in the canopy
Inside the foliage, out of direct sun. Do not squeeze, tear or pierce them — they have an exit hole.
Repeat
Loose mites every one to two weeks; sachets about every four weeks (Biobest). Add Phytoseiulus to any hot spot.
Pesticide sensitivity
Broad-spectrum pesticides can harm it, even some labelled as selective. Cornell lists bifenthrin, abamectin and fenpyroximate as least compatible, and hexythiazox, etoxazole, bifenazate, spiromesifen and cyflumetofen as the most compatible miticides. Check a product →
When to choose something else
Californicus is a slow, steady predator. Choose something else when:
- Spider mites are already webbing plants — Phytoseiulus persimilis acts faster on hot spots; use californicus alongside it
- The crop is tomato — Koppert says not to use its product there, and Cornell says hairy crops need higher rates
- Temperatures stay below about 10 °C — Biobest gives 10 °C as its floor; Amblyseius andersoni tolerates cooler conditions (UConn: active from about 6 °C)
- The main problem is thrips — thrips are alternative food, not a target; use a thrips predator
Where to buy
Suppliers listed alphabetically, not ranked. The same mite is also sold as Amblyseius californicus. helpfulbugs takes no commission and does not sell insects.
- Arbico Organics1,000 to 25,000; sachetsUS
- Biobest (Californicus-System)5,000 / 25,000; 100 or 500 sachetsEU / NA
- Koppert (Spical, Spical Ulti-Mite)25,000 / 125,000; 5,000 in US retail; sachetsGLOBAL
- Sound Horticulture1,000 to 125,000; sachetsUS
Neoseiulus californicus by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.