Phytoseiulus persimilis - Spider Mite Killer


Spider Mite Killer uses the predatory mite Phytoseiulus persimilis for the biological control of the two spotted mite (Tetranychus urticae) often known as red spider mite.

Phytoseiulus predatory mites are the most commonly used form of biological pest control against red spider mite / two spotted mite in greenhouses and protected growing environments. These predatory mites feed on all stages of the spider mite life cycle from egg to adult. Their life cycle is faster than the mites they are feeding on and in suitable conditions they can double their population every two days, consuming around 5 adults and 20 young larvae per day. This leads to a quick reduction in the spider mite population and plant damage.

What conditions do Phytoseiulus need to be effective?

Temperature ranges between 15-25 degrees are ideal for Phytoseiulus to be most active. The predators like slightly higher levels of humidity than the pest spider mites, a relative humidity of around 70% is ideal. If conditions are too dry, predators will begin to move to the bottom of the plant seeking moisture.

If temperatures are too low (under 15 degrees ) Phytoseiulus will begin to struggle and an alternative predator, Amblyseius andersoni should be used to control spider mite.

How long do the predators last?

So long as Phytoseiulus have correct environmental conditions and a source of spider mites to feed on they can reproduce and stay established on the plant. Once there are no spider mite left to feed on, Phytoseiulus will naturally die out after 3-4 days. If infestations are very severe larger numbers will be needed to begin seeing a reduction in pest populations.

How many do I need?

Based on an average plant of 1m in height. We recommend the following application rate;

500 Phytoseiulus per plant

For severe infestations, where leaves show signs of webbing and yellow splotches. We advise doubling this rate and applying spot treatments to areas with large numbers of spider mite.

How do I apply?

Spider mite often feed at the top of plants, so ensure predators are released in this area or in hot spots of activity. Supplied in shaker bottles you can apply the predators by rotating the bottle and gently shaking the contents directly onto the infested leaves of the plants. Phytoseilius can also be applied using distribution boxes which act as small breeding sites for the predators and can be hung onto stems or leaves. Full instructions are provided on delivery.

Can I store Phytoseiulus?

We advise using Phytoseiulus as soon as possible upon delivery, this ensures best results as the mites are fresh. If you must store Phytoseiulus place them into a fridge at temperatures between 6-8 degrees for no more than 1-2 days.


Please Note; Phytoseilius is a living creature and can be affected by any chemical pesticides used within the previous few weeks. As a guide cease using pyrethrum or SB plant invigorator 2 days prior to use and other persistent chemicals or universal bug killers 1-2 weeks before using Phytoseilius. 

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