Honeylocust Spider Mite

Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Chelicerata
Class	Arachnida
Subclass	Acari
Superorder	Acariformes
Order	Trombidiformes
Suborder	Prostigmata
Infraorder	Eleutherengona
Superfamily	Tetranychoidea
Family	Tetranychidae
Subfamily	Tetranychinae
Tribe	Tetranychini
Genus	Platytetranychus

Scientific Name

Platytetranychus multidigituli

Common Name

honeylocust spider mite

Compiled by Whitney Cranshaw, Colorado State University:[1]

Platytetranychus multidigituli (Ewing)
Acarina: Tetranychidae

Host:

Honeylocust

Damage and Diagnosis:

Honeylocust spider mite is a pale green mite that feeds on the underside of honeylocust leaves. As they feed their mouthparts slice the outer cell layers and they feed on the released sap, leaving small flecked wounds. Feeding is particularly concentrated along the mid-rib of the leaf underside, where eggs, old egg shells and/or the mites can usually be found. During heavy infestations leaves turn an off-yellow color and the entire crown be similarly discolored. Premature leaf drop often occurs in years when midsummer outbreaks occur. Problems with honeylocust spider mite are generally limited to trees planted along roads, in parking lots and in similar hot, dry sites.

Summer forms of the honeylocust spider mite are yellow-green and are usually found concentrated along the main leaf vein. In late summer they begin to turn more orange and overwintering forms are bright orange.

Associated Insects:

An eriophyid mite is commonly associated with honeylocust spider mite on leaves of honeylocust and is thought to induce a rusty coloration of infested leaves.

Life History and Habits:

Adult females, orange-red in color and in reproductive diapause are the overwintering stage. Beginning in late summer they cluster around buds or in bark cracks of branches and also may be found in masses on the lower trunk. In late spring, they resume activity, revert to their normal greenish color and begin to lay eggs on leaves. Eggs hatch and the immature nymphs feed on the leaves, molting two times before reaching the adult form. Time from egg stage to adult ranges from 8 to 17 days, depending on temperature. Multiple generations occur and in most years populations tend to increase steadily through July and decline through August. Years where there is unusual spring rainfall or cooler temperatures may see a shift in population peak of about a month.

Management:

Few natural enemies have been observed attacking honeylocust spider mite in Colorado. Among the most important are the predatory plant bug Deraeocoris nebulosus, a predatory mite (Amblyseius fallacis) and a predatory thrips (Scolothrips sexmaculatus)

Honeylocust spider mite problems seem to be associated with dry sites, such as street tree plantings. They are rarely a significant problem when surrounded by irrigated turfgrass that apparently increase humidity.

Honeylocust spider mite is relatively easy to control with several miticides. Dormant season applications of horticultural oils should be effective against the overwintering females on twigs, branches and trunks.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.