Figure 1. Multicolored Asian lady beetle adult. Courtesy: Adam Varenhorst
The multicolored Asian lady beetle is a non-native species of lady beetle that many people utterly detest (Figure 1). Although this particular insect is beneficial by eating aphids, particularly soybean aphids, it also comes with many downsides. During the fall, the adult multicolored Asian lady beetles move into structures (including garages and homes) to spend the winter. Most people know that these beetles are capable of biting when searching for food, and that they can exude a foul smelling yellow-orange substance from their joints. What a lot of people don’t know is that the multicolored Asian lady beetle can also be a pest of orchards and vineyards.
Although the multicolored Asian lady beetle doesn’t directly feed into fruit, it will gladly take advantage of pre-existing entry points made by birds or other insects. Typically, multicolored Asian lady beetle populations are more noticeable during years when large populations of soybean aphids were present in nearby soybean fields. Once soybean begin to senesce, the multicolored Asian lady beetles search out alternative hosts and they are attracted to overly ripe or decaying materials. The most commonly infested fruits include ripe or nearly ripe apples, grapes, and raspberries. The multicolored Asian lady beetles create large cavities that may be filled with numerous adults feeding on the flesh of the fruit. Although the adult beetles can be washed away, there is still a chance that their notorious odor may linger and effect the flavor of the fruit. This is especially true with wine grapes. The adult beetles are difficult to remove from clusters and will taint the flavor of the wine if they are crushed with the grapes.
The best approach for preventing infestations of multicolored Asian lady beetles in fruit is to remove damaged fruit from the tree or bush and dispose of all ground falls. Ripe or decaying fruit will attract the beetles and increase the likelihood of an infestation.