Predatory mites are, in many new age gardener’s opinions, the best way to control spider mites. Predatory mites are mites that do not feed on plants but on other mites, like the two-spotted mite, for instance. Predatory mites can usually be mail-ordered from a horticultural warehouse or purchased online from any number of online gardening vendors.
is referred to by the Cornell University Extension office as ” one of the mainstays of greenhouse integrated pest management.”
The great thing about this species of mite is that it cleans up after itself once the spider mite population is gone, they start cannibalizing on each other, thus decimating their own populations.
is another common predatory mite used to kill spider mites. It is an effective biological control only if temperatures are on average between 44 degrees and 89 degrees Fahrenheit.
- is essentially a variant of the Phytoseiulus persimilis mite brought in from Africa which can stand warmer ambient temperatures than its North American cousins. Longpipes is seeing a gain in popularity among gardeners who would rather deploy a biological spider mite control agent than a chemical or physical control.
The lady bug is tiny, oval, and black and it is a natural killer of pest mites. It is attracted to specific volatile chemical signals given off by the damage the spider mites cause to leaves. It is not just the smell that drives the lady bugs wild; this insect cannot resist the yellowing of the leaves damaged by spider mites. Adult lady bugs can live for over a year and eat up to nine mites an hour or 75 to 100 a day.
Growers chose lady bugs as their biological control agent until U.S. Environmental Protection Agency regulations prompted growers to switch to new pesticides that kill lady bugs. The predatory mite, however, was resistant and could live through spraying s. So predatory mites are now the hunter of choice for spider mites. Some miticides like Azamax do not kill ladybugs.
The Praying mantis is a most interesting and enjoyable beneficial insect to have around the garden and farm. It is the only known insect that can turn its head and look over its shoulder. Mantis lie in wait for their food and when close enough, snap it up with a lightning movement of their strong forelegs. Measurements of their reflexes show they react more than 2 times quicker than houseflies. Mantis have enormous appetites, eating various aphids, leaf hoppers, mosquitoes, caterpillars and other soft-bodied insects when young. Later they will eat larger insects, beetles, grasshoppers, crickets, and other pest insects.
Black hunter thrips
Thrips are primarily phytophagous but a few species are predaceous. Two species, the sixspotted thrips (Scolothrips sexmaculatus) and the black hunter thrips (Aelothrips sp.) are found in tree fruit crops. They mainly prey on the eggs and young of spider mites and do not harm trees. Predatory thrips are rarely found in regularly sprayed orchards, but where soft pesticide control programs are used, they can become abundant and control spider mites. The adult of the sixspotted thrips is about 1/30 inch (0.8 mm) long (see Western flower thrips for general appearance). It is pale yellow with three brown spots on each forewing. The adult of the black hunter thrips is larger, about 1/15 inch (1.6 mm) long, and has a dark body and legs. The forewings of this species are clear with two dark cross-bands joined by a dark bar along the hind margins. Adults of both species can be counted along with other insects in beating tray samples.
Big-eyed bugs are true bugs in the order Hemiptera. The two most common species are Geocoris pallensand Geocorcis punctipes. Both are predators and occur in many habitats, including fields, gardens, and turf grass. Big-eyed bugs are considered an important predator in many agricultural systems and feed on mites, insect eggs, and small insects such as pink bollworm, cabbage loopers and whiteflies. Adult Big-eyed bugs are small (about 3 mm) black, gray, or tan with proportionately large eyes. Eggs are deposited singly or in clusters on leaves near potential prey. They develop with incomplete metamorphosis (there is no pupa) and take approximately 30 days to develop from egg to adult depending on temperature. Both nymphs and adults are predatory, but can survive on nectar and honeydew when prey are scarce. Big-eyed bugs, like other true bugs, have piercing-sucking mouthparts and feed by stabbing their prey and sucking or lapping the juices. Although their effectiveness as predators is not well understood, studies have shown that nymphs can eat as many as 1600 spider mites before reaching adulthood, while adults have been reported consuming as many as 80 mites per day.
Minute pirate bugs are common insect predators that are found in many agricultural crops, pasture land, and surrounding areas. Minute pirate bugs are “true bugs” (Hemiptera) in the family Anthocoridae. Both immature stages (nymphs) and adults feed on a variety of small prey, including spider mites, insect eggs, aphids, thrips, and small caterpillars. Both adults and nymphs feed by sucking juices from their prey through a sharp needle-like beak, which is characteristic of all true bugs.
Adults are very small (1/8″ long), somewhat oval-shaped, and black with white wing patches. Females lay tiny eggs within plant tissues where they are not easily seen. These hatch into nymphs, the immature feeding stage. Nymphs are small, wingless insects, yellow-orange to brown in color, teardrop-shaped and fast moving. Growth from egg to adult takes a minimum of 20 days under optimum conditions. Several generations may occur during a growing season.
The most common species in the Midwest is Orius insidiosus, the insidious flower bug. Another species, Orius tristicolor, the minute pirate bug, is more common in western states. Both immature and adult Orius can consume 30 or more spider mites per day. They are often seen in corn silks, and can be an important predator of corn earworm eggs, which are laid on corn silks. Other reported prey include eggs and small European corn borers, corn leaf aphids, potato aphids, and potato leafhopper nymphs. Occasionally, Orius may even bite humans, but the bite is only temporarily irritating.
Minute pirate bugs are most common where there are spring and summer flowering shrubs and weeds, since they feed on pollen and plant juices when prey are not available. Foliar applications of insecticides to crops can greatly reduce their numbers. Even soil applied systemic insecticides may reduce their numbers because of their habit of sucking plant juices. Diversified cropping systems, use of microbial insecticides, e.g., products containing Bacillus thuringiensis, and use of economic thresholds to minimize insecticide applications, are all practical recommendations to maximize the natural biological control from minute pirate bugs.
Orius are available commercially from insectaries, but specific use recommendations have not been researched. They are shipped as adults in a carrier such as bran, rice hulls, or vermiculite, along with a food source. The carrier can be shaken onto plants, and the bugs will readily disperse and locate prey.