NDSU Extension - Burke County


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Ugly Bugs!

County Agent News
Dan Folske
August 13, 2018 

Ugly Bugs!

            Are all ugly bugs bad? I get a lot of Insect ID questions about bugs that are so ugly they must be bad! Actually, it seems that the reverse is closer to the truth. Most of the really ugly ones are good guys. Or, so it seems based on the photos I get or the insects people bring to the office.

            One common ugly one I get questions about is often described as an orange and black bug with a rough, bumpy surface like an alligator. It is the larval stage ofLady Beetle Lady Beetle Larvathe Lady Bug Beetles and is a voracious consumer of aphids and mites. A couple of other ones I commonly get calls about are parasitic wasps. They look like giant yellow jackets with “stingers” over an inch long. The stingers are actually ovipositors, which the wasps use to lay eggs. Most of these parasitic wasps have larvae which then develop either inside of or next to the larvae of harmful insects using the bad larvae as a food source.

            One ugly one, which is actually bad is the wheat stem sawfly adult. However, I’ve never had one of these brought in for identification because they are quite small and generally only found in fields or grasslands. They were apparently more common from mid June until mid July this year because I have been hearing more reports of sawfly damage found in wheat fields last week. These wasp like flies lay their eggs on the elongating stems of the developing wheat Wheat Stem Flyplant. The developing larvae feed inside the stem and eventually moves down to the base and chews a notch on the inside of the stem where the stem often breaks just before harvest. There is no good control using insecticides because the adult flies have a long emergence window and the larvae are protected by the wheat stem. Crop rotations are helpful but not overly effective because the adult flies are very mobile and fly into the fields from adjoining grasslands. Because of this mobility damage can often be found throughout a field but is generally worse in the field margins.

            Recommended practice for minimizing the damage include swathing, particularly the two outside rounds, using a stripper header since it will get many of the broken heads but leave standing stems containing the larvae of a parasite, which controls the wheat stem sawfly larvae. Another option is to plant solid stem varieties of wheat.

            For more information about wheat stem sawfly and how to manage it go to: https://www.ag.ndsu.edu/publications/crops/integrated-pest-management-of-wheat-stem-sawfly-in-north-dakota





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