Two arthropods known to cause browning and dieback in the northeast are the ubiquitous spruce spider mite (Oligonychus ununguis), and the Maskell scale (Lepidosaphes pallida). The first is a familiar pest to landscape managers. The second is a cryptic, armored scale insect that seems to have escaped the attention of landscapers and researchers alike despite its potential as a major pest of Cryptomeria. The scale has a wide host range and is distributed throughout the South and Northeast. 

The Maskell scale may best be described as a smaller, thinner version of it's close relative the oystershell scale (Lepidosaphs ulmi). The adult female cover is .5 mm. wide, 1-2 mm. long, and translucent brown; the yellow eggs may be seen through the cover. Male covers are smaller. A light infestation on Cryptomeria is hard to diagnose because the scattered scale covers are mostly on the stem and hidden by the spirally arranged, inward curving needles. In heavy infestations the scale covers can be seen out on the needles. Using a 10X hand lens will help nursery growers to detect this minute pest in field plantings. 

In the northeast, Maskell scale seems to attack primarily Cryptomeria. In the South, it has an expanded host range. Dekle (1976) reported it on Cephalotaxis, Chamaecyparis, Cryptomeria, Cupressus, Juniperus, Picea, Podocarpus, Sciadopitys, Sequoia, Taxus, and Thuja in Florida with Juniperus the most commonly infested and seriously damaged host plant. 

This introduced pest is widely distributed throughout the old world where it has been studied. This scale's life cycle has not been seriously studied in the U.S. From occasional observations (Davidson and Raupp, 1993) there appears to be two generations a year in Maryland with crawlers emerging in June and August. 

The scale damages plants by piercing the plant tissue and sucking up cell contents. Early damage symptoms are chlorosis of the needles followed by browning. Severely infested trees show a slow dieback, heavy needle shedding, and a general unthriftiness. Environmental stress from drought or extreme winter weather may intensify the scale feeding injury. Scale infested trees may continue to survive for several years looking less attractive each year until they die. Predator and parasite populations have not been found in sufficient numbers to control this scale in Maryland.

Control 
The key to control involves careful monitoring, early detection of a Maskell scale population, and insecticide spray coverage that makes contact with the pest. For nursery growers who are propagating cuttings of Cryptomeria, examine cutting closely for presence of this cryptic scale and destroy any cuttings with scale. For landscape plants that can be sprayed thoroughly, an application of 3% horticultural oil applied as fine mist can be used in the plant dormant season before budbreak. With careful monitoring in the spring, aided by the use of 10X hand lens, the mobile crawler stage (white in color and about 1 mm long) of the scale can be detected and a 2% horticultural oil can be applied for effective control. The use of horticultural oils will have the least impact on beneficial arthropods, compared to residual, contract insecticides. Examine branches later in the season to determine whether the scale population is under control. Systemic and contact insecticides labeled for scale crawlers should be effective if applied based on monitoring for crawler activity of the Maskell scale. Look for the second generation crawlers in August.