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Katydids in Grapes By Devin Carroll & Chris Million 2010 Katydids are a minor grape pest not covered by UCIPM. They are important pests of other crops, such as nectarines and citrus. It is rarely worthwhile to use a special treatment to treat katydids in grapes, but if a treatment for another pest also controls katydids, so much the better. There are two species. Angularwinged katydid (AWK) has one hatch, in April-May. Fork-tailed bush katydid (FTBK) has two hatches per year. Overwintering eggs hatch in March-April. Maturation takes about 2 months. Newly mature females lay eggs in June. Some new eggs hatch in July-August, and some stay dormant until the following FTBK nymphs with leaf damage in March. year. In grapes as in other crops, katydids feed mainly on leaves, especially young leaves. The holes in grape leaves can be quite prevalent, but usually growers are not very concerned. Extreme populations early in the season may need treatment. Katydids may feed on a few flowers during and shortly before and after bloom. The damaged flowers will fall off, along with many undamaged flowers during shatter. Thus flower damage is of no importance. FTBK nymph with nibbled flower bud in It is not clear whether katydids May. feed on grape berries between bloom and near harvest, but it is not much. The second generation of fork-tailed katydids occasionally chews round holes in grape berries as they near ripening. Most often, we have observed damaged grapes close to leaves in the canopy, where the katydids can step from a leaf to a grape bunch. Grapes hanging free near the cordons seem to be damaged less often. Presumably, feeding holes on near-ripe grapes may lead to rot, but the damage is so rare that it probably is not worth treating. In our experience, high katydid populations seem to occur most often in conventional table grape vineyards. We have not seen as many katydids in raisin, wine, and organic table grapes. This suggests that some pesticides are interfering with biological control. Egg parasites in the family Eupelmidae are a key natural enemy. Spiders and birds are likely predators. FTBK lays eggs in leaves, and Probably katydid feeding, from a AWK in leaves or canes. Eggs are the vineyard with high FWBK numbers in overwintering stage. Thus sanitation by September. discing in leaves during winter will reduce spring populations. Several good worm treatments also control katydids, including Delegate, Entrust, and Altacor. The most effective control is when nymphs are small. Imidan controls katydids at low rates, and may also be used to control beetles, worms or vine mealybugs. Lannate and pyrethroids such as Danitol or Renounce also control katydids along with many other pests, but they are disruptive to biological control of other pests as well.