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Adult Aphytis melinus parasitizing an armored scale.

Adult Aphytis melinus parasitizing an armored scale.

Comperiella bifasciata. This is another commercially available wasp that attacks a variety of armored scales. Females prefer to oviposit in second-instar female scales.The adult wasps emerge from mature scales. It has not been investigated for greenhouse use.

Predators

Lady beetles are the most important predators of armored scales.Their life cycle and basic biology are discussed in the section on predators of soft scales.

Chilocorus bipustulatus. This beetle is an important predator of armored scales in the Mediterranean and Middle East. It also attacks some soft scales. Its life cycle is similar to that of C.kuwanae, but tolerates higher temperatures than C. kuwanae. C.bipustulatus is not commercially available in the United States.

Chilocorus kuwanae—Korean twice-stabbed lady beetle. This is an efficient predator of at least 23 species of armored scale in China, Korea, and Japan. It has been used in other countries for release in fruit orchards and is now established in the eastern United States for control of euonymus scale, Unaspis euonymi.The adults are 1/8 inch (3 mm) long and shiny black with one red spot on each wing cover.They feed on all stages of the scale by chewing holes in the scale covering or by pushing under the scale to feed on the eggs or body beneath. As with other Chilocorus species, the eggs are deposited singly or in small numbers under empty scale coverings or in cracks and other protected places. Shiny black larvae hatch from the eggs in about 8 days.The larvae feed for 2-4 weeks, depending on the availability of food. Each larva consumes several hundred scales during its development. Pupation often occurs in small groups on the plant where the larvae developed. There are three generations per year with extensive overlap of all stages during the growing season.These beetles overwinter as adults that become active when outside temperatures rise above 50°F. It is intolerant of high temperatures and cannot complete its development above 90°F. It is not commercially available.

Chilocorus nigritis. This species, discussed in the soft scales section, is also a good predator of certain armored scales.Two related species, C. baileyii and C.circumdatus,are also available commercially in other countries for armored scale control, but not in North America.

Rhyzobius (=Lindorus) lophanthae.

This polyphagous lady beetle occurs across the southern United States from Maryland south to Florida and west to California. It was introduced into California from Australia between 1889 and 1892 to control black scale, but it became established as a predator of a wide variety of armored scales.The 1/16-inch (2-mm) adults are reddish brown with a faint, green metallic tint and yellowish-brown head, legs, and underside. Adults and larvae consume all scale stages by chewing large, jagged holes in the scale wax armor.R. lophanthae may be sensitive to high temperatures during some of its life stages. It does best at temperatures of 59°-77°F, but can tolerate humidity from 20-90%.This commercially available beetle will also feed on soft scales.

Other predators. Limited control of some armored scales may be provided by green lacewing (Chrysopa and Chrysoperla spp.) larvae.

The larva of the Korean twicestabbed lady beetle, Chilocorus kuwanae.

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