Macremphytus

MacGillivray, 1908

Dogwood Sawflies

Macremphytus is a of in the , comprising at least four described . The best-known member is Macremphytus tarsatus, commonly called the dogwood , which is a significant defoliator of dogwood trees in North America. Sawflies in this genus are herbivorous, with feeding on leaves of . The genus exhibits distinctive larval traits including waxy secretions and behaviors in wood.

Identification

distinguished from () by possessing six or more pairs of fleshy on abdominal versus five or fewer in caterpillars. Early covered in waxy filaments; mature larvae of M. tarsatus display , white, and black coloration. are small, -like .

Habitat

Associated with deciduous woodlands and ornamental landscapes containing plants, particularly dogwoods (Cornus spp.) and trees in the walnut (Juglandaceae).

Distribution

North America; records include Vermont and broader United States.

Seasonality

emerge and from May through July. develop through summer, with mature larvae seeking sites in wood during autumn.

Diet

feed on leaves of plants including grey dogwood (Cornus racemosa), silky dogwood (Cornus amomum), flowering dogwood (Cornus florida), black walnut (Juglans nigra), butternut (Juglans cinerea), and hickories (Carya spp.).

Host Associations

  • Cornus racemosa - grey dogwood, favored
  • Cornus amomum - silky dogwood
  • Cornus florida - flowering dogwood
  • Juglans nigra - black walnut
  • Juglans cinerea - butternut
  • Carya spp. - hickories

Life Cycle

Winter spent as in chamber constructed in rotting wood or structural wood including siding and decks. In spring, larvae pupate. emerge May-July, mate, and females in clutches of 100 or more on undersurfaces of leaves. Eggs hatch and larvae develop through multiple over summer. Mature larvae abandon plants in autumn to construct galleries in wood.

Behavior

initially feed gregariously, skeletonizing leaves; later may consume entire leaves except midveins. Early instars curl beneath leaves when disturbed. Mature larvae bore into wood to create chambers, producing sawdust-like .

Ecological Role

and defoliator of and ornamental trees. serve as food source for and ; waxy secretions may provide defense against and .

Human Relevance

M. tarsatus recognized as occasional pest of ornamental dogwoods and landscape plantings. Larval boring into structural wood, including decks and siding, can cause minor .

Similar Taxa

  • Eriocampa juglandisButternut woollyworm, another with waxy larval secretions; distinguished by preference (walnut ) and pupal in soil rather than larval overwintering in wood
  • Atomacera deceptaMallow , similar larval and waxy secretions; distinguished by plants (mallows/Hibiscus) and different timing

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Sources and further reading