Katydids

Katydids are an occasional pest of blueberry in the San Joaquin Valley. There are two species of katydids found in California blueberries, the angularwinged katydid and forktailed bush katydid. The forktailed bush katydid occurs most frequently in blueberries.

Katydids occasionally become damaging pests in fields that have not been treated with broad-spectrum pesticides or where tillage is not used. High numbers of these pests occur sporadically, and they may cause damage one year and not the next.

Both nymphs and adults feed on leaves or fruit, but the adults are the most damaging. Katydids tend to feed on a small section of a fruit before moving on to another feeding site. Hence, a few katydids may damage a large number of fruit in a short time. Katydids will feed on any size fruit. Feeding wounds heal over and enlarge into corky patches as the fruit expands. Damage to a young fruit can cause it to become distorted as it develops. Nymphs and adults also chew holes in foliage. Smaller nymphs feed in the middle of the leaf, creating small holes, whereas larger nymphs and adults feed on the leaf edge.

In most years katydid management in blueberries is only needed in a few fields in the San Joaquin Valley. These sites are often near alternate hosts such as stone fruits or citrus. In these areas, monitor for katydid migrations from April through May using sweep nets or beat sheets on cover crops and weeds near the perimeter of the fields. Monitor blueberries by looking for feeding holes on leaves and feeding scars on fruit. If significant amounts of fruit are damaged, consider a treatment; damage to foliage is not of economic importance.

To date very little is known about cultural controls for katydids in blueberries. Egg parasites can reduce katydid numbers throughout the year. However, they provide minimal to no control of katydids that mature in overwintering hosts and then migrate to blueberries as adults.