When applied to plants and soil, nematodes hunt for their prey, attracted by the carbon dioxide emitted by the doomed host. Carrying insect-pathogenic bacteria within its gut, the nematode penetrates its host and the bacteria multiply, killing the pest. The nematode feeds on the bacteria and insect's body, then mate and reproduce. A week or two later, young nematodes emerge from the insect's carcass and hunt for new hosts. If you have root weevils notching the leaves of your rhododendrons or flea infestation in the lawn, try applying Sc nematodes.
Spider mites can become a nasty pest in greenhouses, patios and plant rooms during the late summer.
Chemical sprays have little effect once infestation occurs. Fortunately, spider mites can be controlled with predatory mites. For instance, Neoseiulus californicus is a mite that will prey upon the spider mite, broad mite and cyclamen mite. Predatory mites should be released at first sign of spider mite infestation. Botanical insecticides are available at most nurseries locally.