Agriculture: Walnut Pest Management Guidelines

False Chinch Bug

  • Nysius raphanus
  • Description of the Pest

    The false chinch bug is an occasional pest of young walnut orchards. It hibernates as an adult and moves in late winter to preferred weeds, primarily mustard family weeds such as London rocket, shepherd's purse, and common peppergrass, where it stays to lay eggs in early spring. Nymphs are dull gray or brownish red and collect in great numbers on the host plants.


    When weed hosts dry up in late spring, chinch bugs move into orchard trees where they may kill new foliage. This damage can occur within hours because the nymphs apparently inject a toxin while feeding. The leaves dry up and are covered with fecal spots. Damage may be substantial on trees that are 1 to 3 years old. Several generations are produced each year, but damage in orchards usually occurs only in spring.


    • Where damage has occurred, control weed hosts in and adjacent to the orchard to prevent populations from developing in future years.
    • Begin checking weed hosts for false chinch bug in late February and early March, especially in years when moisture is abundant.
    • Mowing and discing cover crops before walnut trees begin to leaf out prevents false chinch bug development and migration.
    • If potentially harmful numbers are found on weeds or cover crops after walnut trees have leafed out, consider spraying the weeds or cover crop with a broad-spectrum insecticide, such as a a pyrethroid; avoid mowing or discing at this time to prevent migration to walnut foliage.
    • If nymphs are found on trees, apply a broad-spectrum insecticide, such as a pyrethroid.
    Common name Amount to use REI‡ PHI‡
    (Example trade name) (hours) (days)
    Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.
    (Warrior II with Zeon) 1.28–2.56 fl oz 24 14
    COMMENTS: Larvicide.
    (Brigade WSB) 8–32 oz 12 7
    1 Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).
    Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of these two intervals is the minimum time that must elapse before harvest may occur.
    * Permit required from county agricultural commissioner for purchase or use.
    Not recommended or not on label.
    Text Updated: 07/17
    Treatment Table Updated: 07/17