Trapping and Identifying Mealybugs in Oregon Vineyards

Introduction

Mealybugs (Hemiptera: Pseudococcidae) are soft-bodied insects that can be from one-eighth to one-quarter-inch long. Adult female mealybugs are wingless and oval-shaped with a white wax coating. Adult males are winged and smaller than the females. Mealybugs are known vectors (spreaders) of grapevine leafroll-associated viruses, produce honeydew and sooty mold growth on grape clusters and the vine, and attract ants. These insects often exist undetected in vineyards due to their cryptic lifestyle. Mealybugs can be found on all parts of the vine, depending on the time of the year, and can remain hidden under vine bark, in clusters and on roots, all not easily visible.

Mealybug species

Several mealybug species are found in Oregon, but few are of economic concern. Grape mealybug (Pseudococcus maritimus) (Erhorn) and vine mealybug (Planococcus ficus) (Signoret) (Figure 2) are of most concern in Oregon. Gills (Ferrisia gilliae), Obscure (Pseudococcus viburni) (Signoret), and longtailed (Pseudococcus longispinus) (Targioni-Tozzeti) mealybugs may also occur.

Signs of mealybugs on vines include honeydew (a sugary liquid excreted by all mealybugs), sooty mold and sometimes the presence of ants on the vine.

For the vine and grape mealybug, a pheromone lure helps growers monitor and detect male mealybugs. This publication details how to place and use pheromone sticky traps for early detection of the vine and grape mealybug.

Trapping guidelines for pheromone traps

To assemble mealybug traps (Figure 3) for grape or vine mealybugs, you must:

1. Obtain or purchase a pheromone lure and delta trap, preferably with a white sticky bottom liner to visually detect the male mealybugs. You’ll need a separate trap for vine mealybug and grape mealybug.
2. Place the pheromone lure (for either vine mealybug or grape mealybug) on top of the sticky bottom liner.
3. Assemble the trap by securing the top with twist ties and folding in the side tabs.
4. Label the trap with the placement date; vineyard block, row and vine number; and lure type.

Where to place pheromone traps

• Place one trap per 30 acres. If an entire vineyard is less than 30 acres, only one trap is necessary. If male mealybugs are found in your trap but the resident population has not been located, or if there is a high risk that your vineyard will become infested, increase the trap density to one trap per 10 acres.

• Begin placing traps in your vineyard in the spring, from late March to June, depending on the region. Continue trapping through October or until the first rain occurs in fall. Most males are typically trapped in late summer or early fall (August and September).

How to identify male mealybugs in traps

• To the naked eye, male mealybugs can be confused with thrips or midges. They also may be confused with springtails, parasitic wasps or winged aphids.

• Use a good light source and a hand lens to identify male mealybugs on traps.

• It can be difficult to see the features of the winged male mealybugs embedded in the sticky surface of the trap. They are small (less than one-eighth-inch long), brownish and have one pair of clear wings. The chest (thorax) is wider than the abdomen (Figure 4a), and there are two long tail filaments (Figure 4b).

• Encourage your neighbors with vineyards to place traps to determine whether infestations also occur on their property.

• Rapid identification of male mealybugs ensures a quick treatment response and a more effective control program.

• Report suspected infestations to your local county Extension agent, crop consultant, the Oregon Department of Agriculture, or an Oregon State University entomologist as soon as possible for positive identification.

Scouting vineyards for mealybugs

• If you find male mealybugs in traps, visually scout those vineyards for the female mealybug. The best time for field scouting is in late summer or fall, before harvest, when the mealybug population is at its highest.