Ladybugs for two-spotted spider mite
Ladybugs are searched for against spider mites almost as often as against aphids. The honest answer is that the convergent lady beetle sold by the tub is sold for aphids, and UC IPM's spider mite guide does not name it among mite predators. The predator to buy is Phytoseiulus persimilis, which feeds and breeds only on web-spinning mites and eats them fast when the humidity is high enough. There is a mite-eating lady beetle, Stethorus punctillum, but it is a different insect, sold separately in packs of 100 or 200 adults for mite hot spots.
Before you act
Everyone's first idea for aphids, and the one beneficial where buying is usually the wrong move. The ladybugs sold by the tub are convergent lady beetles collected from the wild, and UC IPM says most fly away within a day or two of release, even when aphids are plentiful. The larvae do much of the eating, and they turn up on their own wherever there are aphids. How to recognise it, what it is confused with and how to keep it around are on the full Ladybugs profile.
Other controls for two-spotted spider mite
- Phytoseiulus persimilisPredatory mite · 2–50 /m² per release (Koppert); 100+ /m² on hot spots (Biobest data sheet)
- Neoseiulus californicusPredatory mite · 25–125 /m² per release, weekly, at least five times (Koppert); 5 /m² every two weeks as prevention and 100–200 /m² on hot spots (Biobest data sheet); indoors 1–4 per plant, every two weeks, 2–3 times (Arbico)
- Amblyseius andersoniPredatory mite · 20–100 /m² (Biobest); 50–250 /m² weekly (Koppert)
- Feltiella acarisugaPredatory midge · 0.25–25 /m² per release, at least 3 weekly releases (Koppert)
- Stethorus punctillumPredatory lady beetle · 100–200 adults per hot spot, or 1–4 per 10 sq ft, weekly for 3–4 weeks (Arbico; its low rate is every two weeks)