Forage and Field Insects
Alfalfa Weevil in Utah
The alfalfa weevil is a major pest throughout Utah. It is a beetle with one generation
per year. Eggs hatch in the spring, and the grub-like immature weevils (larvae) feed
by chewing on the alfalfa foliage.
Aphids in Alfalfa
Aphids are soft-bodied insects that remove plant sap from stems and leaves. Heavy
infestations can reduce plant vigor, and cause leaves to wilt, curl or become mottled.
Some aphids can vector disease or plant toxins while feeding, and cause plants to
decrease in productivity.
Beneficial and Pest Insects of Utah Alfalfa
Integrated pest management (IPM) is a multifaceted approach to managing pests by using
multiple tactics (e.g., cultural, biological, mechanical, and chemical control) and
the judicious use of pesticides to suppress pests.
Black Grass Bugs
Black grass bugs are native to western North America. Monoculture reseeding of rangelands
may contribute to outbreaks and severe plant damage. Black grass bug control with
insecticides is often not practical to apply or economically feasible.
Cereal Leaf Beetle
Cereal leaf beetle is a serious insect pest of small grains throughout much of the
United States. This insect is of regulatory concern to Utah; the presence of cereal
leaf beetle in grain can restrict exporting to other counties and states.
Community-wide Grasshopper Control
Springtime, while grasshoppers are still nymphs, is the best time for communities
or neighborhoods to work together to suppress grasshopper populations. Treating as
wide an area as possible is the key to success.
About 400 different grasshopper species are native to North America, and most are
well-adapted to forage and grasslands in Utah. Area-wide treatments are generally
more effective than spot treatments because grasshoppers are highly mobile insects.
Grasshoppers and Mormon Crickets: Fighting them for Nearly 100 Years
Utah has millions of acres of rangeland that are prime habitat for many species of
grasshoppers. Left unchecked, grasshoppers may destroy rangeland and compete with
livestock and wildlife for food.
Lygus Bug in Alfalfa Seed
Lygus bug is the primary pest of alfalfa grown for seed in Utah. When in high numbers,
lygus bug can prevent seed production or severely reduce yield potential. Early scouting
can help make management decisions.
Mormon Crickets: A Brighter Side
In a recent appraisal of Mormon crickets (Anabrus simplex Haldeman), Raffelson (1989)
reminds us that these insects are a subject of great concern and dislike among Western
ranchers and farmers.
Pea Aphid Outbreaks Associated with Spraying for the Alfalfa Weevil in Utah
The pea aphid is a familiar pest in Utah alfalfa fields. But because most alfalfa
varieties grown in the state have been bred for pea aphid tolerance (resistance),
growers generally do not need to spray for this insect.
Russian Wheat Aphid
Russian wheat aphid is a common pest of small grains. Controlling volunteer plants
and adjusting planting dates can help reduce aphid outbreaks. Weekly scouting and
timely insecticide applications can protect grain yields.
Spider Mites in Corn
Banks grass mites and two-spotted spider mites are common pests of field and sweet
corn and a wide variety of other plants. Prolonged hot and dry conditions promote
spider mite development.
Western Corn Rootworm
Western corn rootworm can be a serious economic pest in corn because larvae feed on
corn roots, making plants unstable or severely reducing water uptake. Scouting for
western corn rootworm adults can help make treatment decisions for the following year,
and is critical to keeping production costs down.
Wireworms are the larvae (immatures) of click beetles. Adults are elongate, slender,
hardshelled beetles that take their name from their habit of flipping into the air
(sometimes with an audible clicking sound) when they are placed on their backs.