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| Horn, face flies annoy cattle and cost money |
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Horn fly and face fly are two of the most troublesome insect pests of cattle on pasture, according to Dr. Lee Townsend, University of Kentucky Extension entomologist. Horn flies can cost up to 20 pounds of weight per calf, over the summer. They can also cause weight loss in the cow as well. Townsend suggests horn fly numbers can be kept below the economic loss threshold of 100 flies per side of animal with a variety of treatments.
There is no good information on the number of face flies per animal to cause economic loss, Townsend said. However, face flies are very annoying to the animal. Most producers, being concerned about their animals’ welfare, try to keep the number of flies on the animal at a minimum. Face flies can carry pinkeye from animal to animal, but Townsend says this disease occurs in herds even when there are no face flies around.
Dust bags have been used for many years for fly control. Do not use pyrethroid products such as Ectiban or Permectrin if resistance to pyrethroid is suspected or present.
If a back rubber is used to apply the fly control, mix the insecticide with a good grade mineral oil.
Townsend suggests tying 18-inch strips of cloth at 4 to 6 inch intervals along the length.
Dr. Townsend’s research has shown the horn fly numbers can be reduced by up to 70 percent, without the use of an insecticide, using a large walk through fly trap. Insecticide ear tags can provide control of horn fly and may reduce face fly numbers. Horn fly resistance to pyrethroid and permectrins has become significant in Ohio.
For more information on these fly control measures and others including pour-ons, feed additives and an insecticide bolus, go to: http://pest.ca.ukyedu/EXT/Recs/ENT11Cattle.pdf
Scout fields for cereal leaf beetle
Last year as I was checking wheat fields for head scab I found cereal leaf beetle feeding damage above the economic threshold for the first time since the United Stated Department of Agriculture released predator wasp in the 1970’s. This past week I was in a field that was under threshold but still had eggs present. If those larvae hatch and start feeding by the first week of June, the economic threshold of one larvae per plant could easily be reached. Take some time to look at your wheat.
There are several products labeled for control of this insect. Treatment should run in the $12 to $14 range. You need to be aware of the harvest limitations on each product.
They range from 7 to 30 days before the wheat can be harvested.
When scouting an oat or wheat field for this insect, you will get a black, green, and brown stain on your pants and shoes. This is the defecation of the larvae. The insect which in the larvae stage resembles a slug, covers itself in this slime for protection.
The feeding damage also resembles the damage of the slug.
When feeding damage is severe, the field will have a gray or frosted appearance.
An infestation of one larvae per stem can cost as much as 3 bushels per acre at harvest, thus the economic threshold.
There is only one generation per year. The parasitic wasp has done a great job in controlling this insect for more than 30 years, so if populations build, hopefully the wasp will build behind them.
To determine the number of cereal leaf beetle larvae present, count the number on five stems in 10 places in the field.
Do not spray if populations are below one larvae per stem because you will also kill any predator wasp present in the field. |
| 6/3/2009 |
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