Green June beetle (Figure 1), as well as Japanese beetle (Figure 2), is attacking ripening fruit in many parts of the state. This pest keys in on fruit as it softens and the sugar content increases; it is a serious pest of fruit crops at harvest. Reports of high beetle numbers on grapes, blackberries, and, to a lesser extent, various vegetables have been received. This creates a serious problem for growers because pre-harvest intervals on insecticides means management options are limited. In years when populations are low, this is not a problem, but in other years it can result in substantial losses. Numbers have been high in some areas this year.
Many growers would like to have an insecticide that could control green June beetle and Japanese beetle at harvest, but spraying at harvest is difficult. First, the products that are effect against these pests have required pre-harvest intervals (REI) that prohibit their use in the final few days before harvest. The more effective products for green June beetle control are those that have longer pre-harvest intervals; those with shorter pre-harvest intervals are generally less effective. Second, during the pre-harvest period when the more effective products can be applied (i.e., there is enough time to satisfy the pre-harvest interval requirement), green June beetle is not attacking fruit. Neem sprays have been effective in repelling green June beetle for a few days during the harvest period, but Neem needs to be reapplied frequently and is expensive.
Be careful not to harm insect pollinators when using insecticides to control green June beetle. It is best to spray insecticides in late afternoon when pollinator activity is reduced. For small plantings, fine netting may be an option.
By Ric Bessin, Extension Entomologist