Cereal Leaf Beetle
John Van Duyn, North Carolina State University, Entomology Extension Specialist
Cereal leaf beetle (Oulema melanopus) colonizes wheat, oats, and
other small grains. Beetles infest wheat and other grains in the early spring
and often build-up very high populations. The larvae pupate and resulting adults
emerge in late-May/early-June from these fields. The adults emerge as the grain
crops are maturing and migrate to corn fields to find food. If corn is adjacent to
infested small grain plants may become highly infested with the beetles, especially along
edges nearest the small grains. Cereal leaf beetles eat the leaf
surface tissue on whorl stage plants. Feeding scars appear as long and
narrow streaks eaten between leaf veins, usually on the upper
surface. If beetle populations are very high, defoliation can
reduce yield, although leaf feeding is usually cosmetic. However, damage
is often alarming to farmers even if it poses no economic threat.
Beetles do not reproduce or remain for a very long time in corn
fields and, therefore, damage is a single, short term event that
fast growing corn plants soon overcome.
Insecticides are occasionally necessary to
prevent serious defoliation to corn fields or portions thereof.
To evaluate the need for treatment, two factors must be
considered: (1) assessing the % defoliation and (2) determining
if beetles are still present in the field at high numbers; is
the defoliation going to get worse?. Defoliation estimates
should be compared to Table 6-3
to determine potential yield loss. A 5% potential yield loss and a large beetle population
will usually justify insecticide treatment
(see Scouting for whorl feeding insects).
Agricultural Chemicals Manual
North Carolina Cooperative
Return to Vernon James Center Publications Page
This page (http://www.ces.ncsu.edu/plymouth/pubs/ent/ crclb.html)
John W. Van
Duyn Ph D. Extension Entomologist and Wayne Modlin, and Steven Roberson.
Date Created 1/30/01.
Last revised on 1/31/04.
Published by North Carolina Cooperative Extension
Distributed in furtherance of the Acts of Congress of May 8
30, 1914. Employment and program opportunities are offered to all
regardless of race, color, national origin, sex, age, or
Carolina State University at Raleigh, North Carolina A&T
U.S. Department of Agriculture, and local governments
Caution: The information and
recommendations in these Notes were developed for North Carolina
conditions and may not apply elsewhere.