Early Pasture Mealybug Nymphs Found in Victoria Co.

Pasture Mealybug Nymph
Photo by S. Biles

As our pastures green up in the spring, it is important for us to determine when the pasture mealybugs begin to emerge from the soil. In Australia, their research has shown the pasture mealybug is first found in early October. Since their seasons are opposite ours, their October is analogous to our April.  

I have been scouting pastures for the past few months to see when the first nymphs emerge. This morning, 4/3/26, I visited several pastures that had pasture mealybug problems last year. As expected based on what they see in Australia, the first pasture mealybug nymphs were found in the three pastures I checked. The nymphs were very small, but visible. Reading glasses and a 10x hand lens help a lot.

Our current management recommendations have not changed and we suggest you manage pastures to recover from previous damage by making appropriate fertilizer and weed management applications and following good agronomic practices. While there are a few promising insecticides, they are not currently labeled for use in pastures or forage crops and need to be further vetted. Their labels will have to be changed to make them able to be recommended.

We hope to begin our field trials next week to determine how insecticide control of the mealybug can be accomplished. The trials we plan to conduct will evaluate different insecticides and application timing. 

Right now, my working theory is for an application to be made prior to the first generation mealybug reproducing. A second application will likely be necessary to control later emerging nymphs. We will investigate a third application but hopefully one or two applications will be sufficient to prevent forage losses. While this may be reasonable in hayfields and cleared pastures, some pastures are not accessible to spraying equipment so they may not be reasonable to be sprayed.

Prickly Pear Cactus in Bloom
Photo by S. Biles