Pat Munts: Stink bugs put fruit, vegetable crops at risk

Wanted: Dead or Alive; read the poster. A pretty strong statement coming from the Washington State University Master Gardeners.

The flier was dead serious however. WSU is enlisting the Master Gardeners and gardeners across the state to help survey stink bug species found in Washington and hopefully head off one species that can take a physical and financial bite out of our vegetable and fruit crops.

Stink bugs are pretty common this time of year in our vegetable gardens, orchards and houses. The insect is characterized by a shield-shape shell about a quarter of an inch long in shades of green and brown. They are distinctive because they emit an odor when crushed or trapped that has been described as resembling old socks, rotten cilantro or spicy wet wool.

The main reason WSU is asking for help taking inventory of the stink bug is that one particular species of the insect, the brown marmorated stink bug, can do heavy damage to our commercial apple, pear and vegetable crops. It has been found in Clark and Skamania counties and state agriculture specialists want to keep a close track on it. They also want to know what other species of the insect are here, including some native ones. In a 1988 survey, 23 species were identified and by 2014, the number had grown to 47.

Stink bug females winter in protected areas under lumber wood piles, piles of weeds and other garden debris left on the ground. They emerge in the spring and lay clusters of 20 to 30 eggs on the underside of leaves. Nymphs begin emerging in early June and go through five growth stages feeding on plants as they grow. Both nymphs and adults are quite mobile so they will move in a wide area.

They feed on a wide range of crops including tomatoes, peppers, beans, berries, apples, pears and other crops. They have piercing-sucking mouth parts that are used to sting the fruit and then feed on the flesh underneath. The damaged area eventually turns brown, destroying the fruit’s edibility.

To control them, remove wood and lumber piles and clean up garden debris. Mow weeds near the garden to remove potential hiding places. Researchers are evaluating a parasitic wasp that might help control the brown marmorated stink bug, but its release is several years away. Rescue, the Spokane company that supplies the iridescent wasp traps, makes a stink bug trap that draws in the insects using pheromones.