Forage and Field Insects

    Forage and Field Insects

    Alfalfa Weevil in Utah

    alfalfa weevil

    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.Download

    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 bug

    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

    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.

    Clover Root Curculio

    cereal leaf beetle

    The clover root curculio is an important agricultural pest in forage crops. Adult beetles feed on foliage while the more damaging larval stage feeds on roots. Heavy larval feeding has been associated with reduced stand establishment, disruption of nutrient and water uptake, and reductions in forage quality and yield. Download

    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. Download

    Grasshoppers and Mormon Crickets: Fighting them for Nearly 100 Years

    mormon cricket

    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

    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

    mormon crickets

    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

    pea aphid

    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

    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

    spider mites

    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

    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. Download



    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.