I bought these
Amblyseius Cucumeris slow release packs. They are predatory mites, and cost only $5 a pack.
I bought them for Thrips, but reading up on them;
seems like these would take care of spider mites as well?
Target Pests:
Western flower thrips (Frankliniella occidentalis).
Onion thrips (Thrips tabaci)
also Cyclamen, Broad and Rust mites. Product information: About 60% are female. Well-fed females will lay up to 3 eggs per day for 35 days. Their eggs are round, transparent and 0.14mm (0.01 inch) in diameter and usually deposited on hairs on the underside of leaves. Cucumeris adults and immatures are shipped with a bran carrier.
They are available in two types of packaging:
Release Rates: Relatively high introduction rates are required because thrips can reproduce nearly twice as fast as Cucumeris and Cucumeris only feed on immature thrips, not adults. Rates will vary depending on crop and level of pest infestation. Typical rate is 5 predators per square foot. Using bulk container 10-100 Cucumeris per plant weekly as needed. As a starter culture for young plants, place 25 Cucumeris per plant at the base of the stem Lifespan of Cucumeris: A complete life cycle takes 10-12 days at 68° F. Newly hatched larvae do not feed until they molt at 2 days old. They feed for another 7 days before becoming adults. Adults live for up to 30 days. Description Like most of the Neoseiulus spp., N. cucumeris are tough, flexible predators. These happen to prefer thrips, mostly the immature stages. N. cucumeris are shipped as adults, immatures and eggs (the latter are not part of the guaranteed count) in a loose bran-flake carrier. With this medium, these predators are supplied three different ways: a bulk product for fast distribution and consumption; a pre-punched packet product for slow preventive releases over an 8 week period; and a packet which is not pre-punched that must be torn open and immediately distributed. The latter is designed for extremely small scale use. N. cucumeris, in either form, can prevent thrips from becoming intolerable. The bulk unit and small quick release packet can provide control. Some of the species they can devour include: the western flower thrips (Frankliniella occidentalis); the flower thrips or eastern flower thrips (F. tritici); the onion thrips (Thrips tabaci); the greenhouse thrips (Heliothrips haemorrhoidalis); and possibly the melon thrips (Thrips palmi), too. Other pests which can be impacted by these predators include cyclamen mites (Phtyodromus =Steneotarsonemus pallidus), broad mites (Polyphagotarsenomus =Hemitarsonemus latus) and, to a slight degree, tomato russet mite (Aculops lycopersici). And, as Neoseiulus spp., these predators may eat other pests as well.
Cucumeris is a species of predatory mite that feeds on immature stages of thrips. It also feeds on pollen, two spotted mites and other species of mites. Cucumeris adults are pear-shaped, tan colored mites, less than 0.5mm (1/50 inch) long.