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ISSUE 3  May 20, 1999

NORTH DAKOTA GRASSHOPPERS FOR 1999

    Grasshoppers are probably having a tough time getting started with the recent wet, cool weather.
There should be some hatching underway. Traditional hatching sites, such as ditches and field borders
may be very wet, which will delay hatch.

    The outlook for grasshoppers is down considerably from previous years. It is still wise to anticipate
some very localized hot spots. These sites will correspond with areas that had adult grasshoppers
present last fall. Newly hatched grasshoppers are small (about the size of a kernel of wheat) and hatching
sites require more than a casual inspection. Field crop management decisions are based on the number
of grasshoppers per square yard. Estimate populations by moving through an infested area and counting
the number of grasshoppers that jump or move within a square foot area. Keep a record of your square
foot counts. Divide the total number of grasshoppers counted by the total number of samples taken, then
multiply by nine to calculate the number of grasshoppers per square yard. Refer to the table to evaluate
damage risk.

Grasshoppers per Square Yard =

Infestation rating

Nymphs

Adults

Margin

Field

Margin

Field

Light

25 - 35

15 - 23

10 - 20

3 - 7

Threatening

50 - 75

30 - 45

21 - 40

8 - 14

Severe

100-150

60 - 90

41 - 80

15 - 28

Very Severe

200+

120+

80+

28+

 

Rainfall Effects on Grasshoppers
• Cloudy, wet weather for 1+ weeks
        Promotes fungal pathogens, prolonged period of wet weather important
• Heavy rains during emergence
        Kills young grasshoppers, by trapping them in the soil or physically washing them away
• Drought or lack of rain
        Poor egg hatch, hoppers starve from lack of food, and low egg production by adults

   

WHAT’S THE BZZZZZZZZ . . . MOSQUITOES

    Mosquitoes are already buzzing, but when it warms up they will be abundant. The mosquitoes that are
buzzing about are the flood water type. Their eggs have been laid in damp soil near areas that pond on a
regular basis. When water is present, the larvae hatch from the eggs. It will take about 14 days for larvae
to emerge as adults.

    Many attempts to manage mosquitoes focus on controlling the larvae. This is the time when they are
confined and most concentrated. However, with the saturated soils and most recent rains, there can be
numerous breeding sites around, and difficult to treat them all adequately. Where standing water is a
problem around the home or farmstead, one of the recommended treatment programs is the use of
Bacillus thuringiensis var. israelensis (sold as Mosquito Dunks®, Bactimos®, Teknar®, and
Vectobac®). Mosquito Dunks®, packaged as briquets, are slow release (working for about 30 days).
Also, they remain effective even with the alternate wetting and drying that occurs in these ponding sites.
Local availability of the products may be the challenge.

    Controlling adult mosquitoes is a big task because of their mobility. Generally, the larger the area
treated, the more successful the control. Even then, the results are temporary, as new adults migrate
into the area or emerge from breeding sites. Around the home, control is most practical for short
term reductions of mosquitoes, such as for a summer picnic. In those cases, treat 12 to 24 hours prior
to the event. This insures the spray has dried on vegetation before people are present. It will also reduce
the mosquito population before the guests arrive.

    For most homeowners, sprays containing malathion, permethrin, or carbaryl (Sevin®) should be
directed at vegetation where mosquitoes rest during the day. Treat at dusk or early in the morning.
Around a farmstead, there is one other option. Farmers who use Tempo® to treat grain bins will discover,
when they read the label, that this product is approved for use to treat landscape areas (shrubs and
tall grass) for the control of several nuisance pests, including mosquitoes. This product should be used
only by licensed applicators. It is NOT approved for application to edible crops in the garden.

    Finally, the best protection from mosquitoes is still the use of personal repellants containing DEET.
Protection lasts from 1 to 5 hours. Follow these general guidelines for their use:

    Use just enough repellent to cover exposed skin and clothing. Do not use under clothing. Reapply as
necessary, but avoid overexposure.

Phillip Glogoza
Extension Entomologist
pglogoza@ndsuext.nodak.edu


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