The Black Hunter, Leptothrips mali (Fitch)

I. Introduction: This is the most economically valuable predatory thrips in eastern U.S. orchards although populations of other predacious thrips [Haplothrips faurei (Hood), Scolothrips sexmaculatus (Pergande) and H. subtilissimus Haliday] occasionally play significant roles. It is solitary in habit but very active, however its predatory potential is limited by its low reproductive potential.

II. Hosts: Plant: Normally found on most deciduous fruit trees supporting suitable insect and mite prey populations.
Insect: Economic pests species that serve as major hosts of the black hunter include primarily plant feeding mites, scales, aphids, moth eggs, leafhoppers, and other thrips. The European red mite, twospotted spider mite, and apple rust mite are the principal orchard pests with which this predator interacts and plays a significant predatory role.

III. Description: Black hunter adults (pictured above) are slender, sharply pointed, blue-black insects that are approximately 7/100 inch (1.75 mm) in length. To the unaided eye the insect appears uniformly black with the exception of its silvery white wings. The eggs are translucent white, oval, and slightly less than 0.5 mm in length. Larvae (pictured below) are almost colorless on hatching but soon acquire a uniform dark maroon color as they mature. Pupal stages are also dark maroon but have yellowish white appendages.

IV. Biology: Adults overwinter in many different sheltered locations on trees and tend to aggregate in suitable locations. They become active in the spring and commence searching for prey among the buds, leaves and blossoms. Oviposition is normally on the undersides of the leaves near the mid-vein. The entire life cycle from egg to adult may be completed in 19 days at 85°F (29.4°C) but is slower at lower temperatures. Most females only lay one or two eggs thus population increase due to reproduction is slow.

V. Injury: This insect does not injure fruit or foliage and tends to function well in concert with other predatory species in an orchard environment.

from a chapter in the Mid-Atlantic Orchard Mnitoring Guide, entitled Mite Predators,
by L.A. Hull and R. L. Horsburgh

E-mail to: Douglas G. Pfeiffer