Case-Bearing Leaf Beetle, Neochlumisus platani (Brown)

Leininger, T.D; Solomon, J.D.; Wilson, A. Dan; Schiff, N.M. 1999. A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore. Gen. Tech. Rep. SRS-28. Asheville, NC: USDA Forest Service, Southern Research Station. 44 p.

Importance.-This beetle is known from Massachusetts west to Colorado and south to Florida and Texas. It feeds on sycamore foliage and prefers young trees. Defoliation may result in loss of growth and aesthetic value, but no crown dieback or mortality has been associated with this insect.

Identifying the Insect (fig. 5a, b).- Adults are peculiarly shaped leaf beetles with a rough, knobby, brownish body surface, 4 to 5 mm long, resembling the brown excrement pellets of large caterpillars. When disturbed, beetles feign death and fall from the plants. Larvae are white with black heads and legs, 5.4 to 6.5 mm long, and live in dark-brown cases made of fecal excreta, which conceal all but the head and legs.

Figure 5a. - Larval case Photo by Lacy L. Hyche, Auburn University

Figure 5b. - Larva removed from case.

Identifying the Injury (fig. 5c, d).-Both adult beetles and case-bearing larvae are found feeding on young foliage. Small, scattered holes appear in the leaf. In time, the holes are enlarged and, typically, uniformly distributed over the leaf surface. Trees may appear “ragged” from heavy leaf feeding but are seldom completely defoliated.

Biology.-Overwintering beetles appear on the foliage of host trees in April and May. Females lay tiny, bell-shaped, excrement-covered eggs singly and on short stalks on the undersides of leaves. Young larvae construct and live within cases made of their own frass. Pupation occurs within the case attached to the underside of a leaf. Highest populations occur in early summer. Only one or two generations occur per year.

Figure 5c. - Close-up of feeding damage. Photo by Lacy L. Hyche, Auburn University

Figure 5d. - Tree with feeding injury.

Control.-Parasites and predators usually keep populations under control.