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Extension Entomology

Alfalfa Update

–by Dr. Jeff Whitworth and Dr. Holly Davis

Potato leafhoppers are rapidly increasing throughout alfalfa fields in north central Kansas for two reasons:  1) potato leafhopper adults are still migrating in and 2) the eggs are hatching and nymphs seem to be everywhere.  These nymphs are very small and very shy – which means they are easily under counted as they hop to the underside of leaves, or even off the leaves, at the least disturbance.

Alfalfa weevils mating—(photo by T. Sexton)

Parasitized Alfalfa Caterpillar

Alfalfa weevil adults have mostly migrated out of alfalfa fields in north central Kansas, however there are a few that pupated late and that are just emerging out of their pupal cells.  Interesting, at least to us, was that some of these adults were mating (see picture).  Most of the literature reports alfalfa weevils mating in the late summer, fall/winter  —  not soon after becoming adults.

Alfalfa or garden webworms are also relatively common in alfalfa, where they may cause a problem in new alfalfa, and soybeans.  The next generation will probably be more problematic in small soybeans because there will probably be more webworms as this generation is more of a “spring board” generation.

Alfalfa caterpillars (see picture of larva with attached parasitoid eggs) are also quite common in alfalfa fields as are the white and/or yellow butterflies that they develop into.  However, they have not ever been found in densities great enough to cause any negative impact on yield.

 

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