Compiled By:
Thomas A. Ewart
22 Jul.’99

OAK LACE BUG

Corythucha arcuata, (Say), 1832

(Note: the generic name, Corythucha is commonly misspelled ‘Corythuca’)

General:
Oak Lace Bug is found only in the Western Hemisphere and is one of 15 known species found in the north east section of North America. They can be found South to Alabama, North to Quebec and West to Texas.
Evidence shows that Oak Lace Bug is host specific and feeds only on oaks, however it appears to prefer certain varieties and especially the white oaks. There is however, a subspecies, Corythucha arcuata var. mali, that has been known to also feed on chestnut, apple, rose and to a lesser degree, maple.

Description:

Adults:
Approx. 3.0-3.3 mm long and 1.6 mm wide, dull, light colored, flat, winged (true) bugs. And just as their name sake implies, the wings are made up of a transparent lace-like structure. The lace work pattern is unique for each species. There is a hood-like structure over the insect’s head. The adults are not strong fliers and move slowly. They tend to feed in groups.

Eggs:
Approx. .56 mm long, sub-cylindrical in shape, smooth and shiny black. They’re covered by the adult female with a protective rough coating. Although single eggs can be found, they’re usually laid in clusters of 25-50 and it’s not uncommon to find over 100 eggs on a single leaf.

Nymphs:
They’re much darker than the adults, oval in shape and covered with spines. Like the adults they're slow moving and tend not to fly.


Life Cycle:
The adults over winter in the bark crevices, in the duff or under stones, etc.,
at the base of trees. The adult females move to the host plant in the spring and lay eggs on the lower leaf surface, normally near the larger veins. Egg hatch is in mid May. The nymphs have 5 instar stages with a molt between each stage. A complete cycle from egg to adult will take between 30-45 days. Several generations may
occur in a single season with both nymphs and adults feeding together later in the summer.

Damage:

Both the adults and nymphs feed on the lower leaf surfaces by sucking plant juices though their piercing mouth parts. This feeding produces yellow or whitish spots on the upper portion of the leaf. The insect also deposits a hard, varnish-like frass on leaf surfaces, called tar or resin spots. Added to this, the discarded nymphal skins and eggshells, which all together can leave a tree in an unsightly state. Heavy infestations cause foliage discoloration and possible early defoliation, especially during drought periods.

Control Options:

-Note that Oak Lace Bug damage appears more prominent on sunny sited trees.
-On smaller specimens, a strong, stream of water can wash off the newly hatched nymphs
-Conserve natural predators like green lacewings and assassin bugs
-If an infestation occurs that merits a pesticide application, note that many controls are currently
labeled for Lace Bugs. Refer to your local Cooperative Extension Service for recommendations.


References

Bequaert, Joseph C., (1951) Entomologica Americana, A Journal of Entomology, Volume 31

Nielsen, G.R. (1997) Lace Bugs, University of Vermont Extension ; EL 153

Shetlar, David J. Lace Bugs, Ohio State University Extension Fact Sheet HYG-2150-91

Solomon, J.D. (1987) Oak Pests: A Guide to Major Insects, Diseases, Air pollution and Chemical Injury