Symptoms Adults are most abundant in July and August, flying about and feeding actively on warm, sunny days. They prefer to feed on ripe bramble fruit exposed to sunlight. Bramble cultivars that bear fruit late in July through mid-September may be damaged severely by adults feeding on mature fruit. When such beetles are removed, holes eaten into the berry are conspicuous. Fruits may be gouged in irregular shallow patches or nearly devoured.
Infestations can be so severe that the fruit is left unmarketable.
In addition to damaging the ripe fruit, the exposed injured fruit is susceptible to fruit rots. Beetles flying from one fruit to another carry rot pathogens along with them, aggravating this problem. Japanese beetles attacking fruit of ripe red raspberries. A secondary injury to bramble crops by Japanese beetles is often due to feeding on leaves. In severe cases, foliage exposed to sunlight may be completely skeletonized.