Unusual cereal leaf beetle numbers
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Some
wheat fields in both northern Ohio and south central Michigan have
unusual numbers of cereal leaf beetle adults this spring. From an
entomologist perspective, this is exciting, since cereal leaf beetle
problems are fairly rare, and it is interesting to see them. Adults
beetles are very distinctive metallic, dark blue-black insects with a
red thorax. Females lay one to several yellow-orange eggs on the top
surface of wheat leaves. The larvae are yellowish, slug-like, and have a
fantastic anti-predation strategy. They cover themselves with a moist
mixture of mucus and excrement. Larvae scrape or eat leaf strips.
In most years, cereal leaf beetle populations are very low because of
biological control. From a management perspective, at this time it is
more of a curiosity, but populations bear watching. The most efficient
way to scout now is to sweep wheat fields – an interesting population
would be one or more adults per sweep. I would appreciate knowing about
fields with large numbers of adults or larvae. Please email me at:
difonzo@msu.edu.
Below are a few web links to cereal leaf beetle information and
pictures. Note that these publications are almost 10 years old. While
the biology and ecology information probably hasn’t changed, do not use
the insecticide recommendations. If larval populations do eventually
increase in some fields, the MSU Insect Guide E1582 does have current
integrated pest management recommendations, insecticide products or
rates. There are two different thresholds for larvae. Three eggs
or larvae per plant at boot stage and one or more larvae per flag leaf
after boot stage or 25 eggs or larvae total per 100 tillers.
Photos of cereal leaf beetle:
- Cereal Leaf Beetle Biology and Management, Virginia State University, 1999 http://www.ext.vt.edu/pubs/entomology/444-350/444-350.html
- Managing the Cereal Leaf beetle in small grains and corn, North Carolina State Univ., 1997
http://www.ces.ncsu.edu/depts/ent/notes/Grain/smg_3.html - Cereal leaf beetle publication from Oregon State University, 2000 http://extension.oregonstate.edu/catalog/pdf/em/em8762.pdf
Note that cereal leaf beetle should have a special place in the hearts of all you native Michiganders, since Michigan was the original introduction point of this non-native pest. Cereal leaf beetle was first discovered in 1962 in Berrien County. A large and eventually very successful biological control program was focused in the state at a USDA-APHIS insect facility in Niles and at Michigan State University in the 1960s and 70s.
