If you grow lentils, peas, or chickpeas in Montana, you’ve likely seen the effects of insect pests firsthand. As pulse acreage across the state has doubled in recent years—climbing from just over 600,000 acres to more than 1.2 million—growers have also seen an increase in pest pressure. With Montana now producing nearly half of the nation’s field peas, the stakes are high.
So, what are we up against? Some of the most common offenders include pea leaf weevils, pea aphids, lygus bugs (Lygus lineolaris, L.borealis, L.keltoni and L.elisus), armyworms, cutworms, wireworms, grasshoppers, and leafhoppers. And while the pea leaf weevil has been a well-known pest for years, growers are now seeing more economic damage from pea aphids and lygus bugs, too.
One particularly concerning newcomer is the pea weevil (Bruchus pisorum), which first began showing up in Montana prior to 2010. Since then, it’s raised alarms because it can spread quickly and wreak havoc on seed quality. These beetles lay their eggs on pods, and the larvae burrow into the seeds—rendering them unfit for human consumption and reducing germination rates. Infestation levels can reach as high as 70%.
Montana State University’s Western Triangle Agricultural Research Center (WTARC) is taking action.
Their research has shown promising results. Pitfall traps baited with pheromones caught more pea leaf weevils than other trap types. And in the lab, a product called Entrust WP (spinosad) outperformed other biopesticides for controlling pea leaf weevils. Mycotrol ESO and Xpectro OD also showed moderate effectiveness.
WTARC has also teamed up with the USA Dry Pea & Lentil Council to conduct a multi-site survey of the pea weevil’s distribution. They’re checking fields and grain elevators across the Hi-Line to assess damage and spread. Depending on what they find, the next step may include applying for USDA approval to introduce a natural enemy of the weevil: a tiny parasitic wasp called Uscana senex, which can control the pest by parasitizing up to 82% of its eggs.
Looking ahead, the WTARC team isn’t stopping at just one pest. Their goal is to develop a broader Integrated Pest Management (IPM) strategy tailored for Montana pulse crops. This includes testing resistant varieties, fine-tuning treatment thresholds, evaluating both synthetic and natural pest control methods, and studying how those treatments affect beneficial insects.
For pulse growers, this research couldn’t come at a better time. With crop diversity on the rise and global cereal crop prices under pressure, pulses continue to offer a promising path forward—so long as we stay one step ahead of the bugs.
▶ Have questions about pest management or want to get involved in research efforts? Contact WTARC at 406-278-7707 to learn more.
