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Recognition of imported lady beetles in the tribe Scymnini released in Eastern North America

Informally Refereed

Abstract

Adults of lady beetles in the tribe Scymnini imported for biological control of hemlock woolly adelgid, Adelges tsugae Annand, in eastern North America can be readily distinguished from native lady beetles (Coccinellidae). The imported lady beetles are in the genera Pseudoscymnus and Scymnus (Neopullus), both of which are Palearctic. These taxons have characteristics that can be used to separate them from Nearctic lady beetles. The most useful morphological feature is that the number of antennal segments is less than 11; ten-segmented in Scymnus (Neopullus) and nine-segmented in Pseudoscymnus. Elytral patterns and coloration also can be useful in field recognition. Larvae of the imported lady beetles are all in the tribe Scymnini, which can be distinguished from lady beetles in other tribes. A characteristic of the Scymnini is the wax covering of the last two larval instars and, for most species, the body lacks pronounced spines and is neither black or heavily sclerotized. Identification of a Scymnini larva to the genus level requires careful microscopic examination. Pseudoscymnus tsugae larval antennae have been described as one-segmented, but our examination indicates that they are two-segmented. Scymnus (Neopullus) larvae have three-segmented antennae.

Keywords

Scymnini, native lady beetles, Scymnus, Pseudoscymnus, adult identification

Citation

Jones, Lynn A.; Montgomery, Michael; Yu, Guoyue; Lu, Wenhau. 2002. Recognition of imported lady beetles in the tribe Scymnini released in Eastern North America. In: Onken, B.; Reardon, R.; Lashomb, J., eds. The hemlock woolly adelgid in the eastern United States symposium; 2002 February 5-7; East Brunswick, NJ. East Brunswick, NJ: New Jersey Agricultural Experiment Station and Rutgers University: 335-343.
https://www.fs.usda.gov/research/treesearch/35502