A newly published Extension Bulletin, PNW696, is titled “Integrated Pest Management for the Wheat Head Armyworm Complex in the Pacific Northwest.”
Since 2005, the wheat head armyworm has caused intermittent damage to wheat and barley crops in the PNW.
The two insect species found responsible were initially dubbed the “true” and “false” wheat head armyworms. As these species are closely related, we now refer to them as the wheat head armyworm complex (WHAC).
This publication covers identification, biology, and integrated pest management for WHAC. We emphasize pest monitoring and field scouting methods, and also discuss natural insecticides.
Authors are Diana Roberts, WSU Extension; Silvia I. Rondon, OSU Extension; Peter J. Landolt, USDA-ARS.
Despite their name and characteristic male chirping, Mormon crickets are not true crickets, but rather shield-backed katydids. These pests got their name by endangering the livelihood of Mormon pioneers in the mid-1800s. Pest outbreaks are common and typically occur when conditions are favorable for their development. Some outbreaks can last for up to 20 years. Mormon crickets are voracious feeders that attack a wide variety of field and forage crops, small grains, grapes and fruit trees.
Mormon crickets are large insects (1.5-2 inches) with variable coloration, from beautiful green or purple coloration of solitary individuals to dull black, brown and red coloration of swarming individuals. Females have a long ovipositor present at the end of the body that is used for laying eggs. Although adult insects do have ornamental wings, they are flightless. However, this doesn’t stop them from covering large distances during the swarming phase (up to 1.5 miles per day, 50 miles per season), eating everything in their path and having devastating effects on agricultural production.
Mormon crickets usually have one generation per year, with some exceptions at higher elevations where they require 2 years to complete the life cycle. Adults mate in early summer, after which females lay eggs in the ground. Each female can lay over 100 eggs. Eggs hatch the following spring (March-May) when soil temperatures reach 40 °F. Nymphs pass through seven instars (60-90 days) before reaching maturity and 10-14 days later mating occurs. Nymphs resemble adults in appearance but are smaller and lack wings. Adults feed throughout the growing season.
Although Mormon cricket outbreaks are common, populations tend to build up fairly slow and are easily predictable. Insect monitoring is necessary for a timely risk assessment and the development of effective control measures. More information on pest activity and risk areas can be found on the USDA APHIS official website (https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/grasshopper-mormon-cricket/ct_grasshopper_mormon_cricket).
For information on how to properly control these pests contact your local County Extension office. Dale Whaley is an extension specialist for Douglas County. He can be reached by email (email@example.com) or by phone (509-754-8531).
Insect samples or pictures can be sent for proper identification to David Crowder, Associate Professor in the Department of Entomology at Washington State University (firstname.lastname@example.org) and Ivan Milosavljević, Research Associate (email@example.com) in the Department of Entomology at Washington State University.
For more information on Mormon crickets use these useful links: