Lacy Hyche 

The sycamore, a native forest tree, is used widely as a shade, ornamental, and green-space landscape tree in many urban and suburban areas. The tree grows rapidly, has large green leaves, a spreading crown, and provides welcome shade in summer. But that which provides shade also provides shelter and ideal habitat for several species of harmful insects. One of the most common of these is the sycamore lace bug, Corythucha ciliata. Leaves of sycamore are its favorite food and breeding site, so where there are sycamores there will likely be lace bugs, often in troublesome abundance. Results of AAES research on insects of Alabama trees provide information on habits and importance of this common shade tree pest.

The adult (Figure 1) is a small, fragile bug with membranous lace-like wings that are characteristic of lace bugs (hence the common name). The bugs overwinter as adults in hibernation in protected sites, often in groups under loose bark of host trees (Figure 2). Adults emerge from hibernation following development of new leaves in spring as early as April in the Auburn vicinity and feed on the undersurface of leaves.

Fig. 1. Sycamore lace bug adult, actual length is about 1/8 inch.

Fig. 2. Group of lace bug adults in winter hibernation under bark of the host tree.

Lace bug adults have sucking-type beaks and feed by piercing leaf tissue and extracting leaf sap. Leaf tissue at points of feeding dies and loses its green color. The resulting stippling effect (Figure 3) is typical lace bug damage. Subsequently, females lay eggs on the underside of leaves.

Fig. 3. Typical lace bug damage. At left, early damage by adults; at right, later damage by nymphs and adults.

The small, spindle-shaped eggs are usually placed upright in small groups at junctions of midrib and lateral veins (Figure 4). Hatch occurs within a few days and nymphs, the immature stage (Figure 5), feed on the undersurface in the manner of adults. As nymphs grow and feeding progresses, stippling spreads (Figure 3-right) and heavily infested leaves may become completely discolored, die, turn brown, and drop prematurely.

Fig. 4. Group of lace bug eggs; most have hatched.

Fig. 5. Lace bug nymphs and adults feeding on the undersurface of sycamore leaf. Dark, shiny speckling is excrement deposited by the feeding bugs.

Nymphs usually complete development in about 30 days; the cycle from oviposition (egg-laying) to new adult is usually complete in five to seven weeks. Thus, several generations may occur in a season, and lace bugs may be present into late summer for as long as suitable foliage is available.

Both adults and nymphs of the sycamore lace bug feed on the underside of leaves; however, evidence of damage (the stippling of leaves) shows most clearly on the top surface. The undersurface of infested leaves is usually densely speckled with dark, shiny droplets of lace bug excrement (Figure 5).

The lace bug can usually be found on sycamores growing in natural stands, but, as a pest, it is far more important in the urban/suburban forest. Here, damage to leaves destroys or severely reduces the aesthetic value of shade and landscape trees. In addition to damaging leaves, the lace bug sometimes interferes with normal people-usage of shade trees. In mid- and late summer, adults sometimes become very abundant and, if disturbed, often drop from leaves and settle on objects below. Thus, people sitting “neath the spreading” sycamore tree may find adult lace bugs on their clothing and in their hair. Lace bug adults do not bite or sting; nevertheless, their presence can be annoying. While lace bug attacks do not usually seriously threaten the health and survival of trees, control of infestations on shade and ornamental trees is sometimes desirable. For recommendations on control of lace bugs, contact appropriate county extension personnel.