Information for Fruit Growers
- Update for grape growers, by Rufus Isaacs, small fruit MSU Extension specialist, Department of Entomology, Michigan State University
A multi-colored Asian lady beetle searches for prey on a blooming pear tree. Photo: R. Isaacs.
The multi-colored Asian lady beetle is a beneficial insect that has become established throughout the eastern United States. Originally introduced to help manage tree fruit pests, it has become a nuisance for homeowners and for some agricultural crops. In recent years, it has caused problems for growers of fall-ripening fruit who find the beetles on and in their fruit during harvest. However, this insect also helps fruit growers during the summer months when adults and larvae provide biological control of many soft-bodied insects, including aphids and leafhoppers. During the fall when the adult lady beetles begin to search for energy and sheltered sites for overwintering, fruit crops can provide both of these resources and large numbers of beetles can infest fall-ripening fruit. Raspberries, blackberries, grapes and peaches are particularly affected.
As their name suggests, adult Asian lady beetles can take on many different color forms, varying from yellow to orange and red. Their spots may be dark on the wing covers or they may be faded or absent. Even the number and size of spots varies.
Photo: Tyler Fox
Photo: Howard Russell
Photo: Howard Russell
Many beetles have a straw-colored pronotum (top covering of middle body part) with markings that fuse into a regularly to irregularly shaped "M" if viewed from the front, or "W" if viewed from behind.
The adult beetles are approximately a quarter-inch long with a domed, round to oval shape. They are similar to many of the native species of lady beetles that do not cause homeowners or fruit growers problems. Native lady beetle species typically overwinter in sheltered sites outdoors and do not seek homes during fall.
Immatures (larvae) are covered with tiny, flexible spines that do not sting (see photo at right of larvae eating aphids). Their body is alligator-shaped and they can rapidly move over leaves and branches, where they eat aphids and other soft-bodied insects. Eggs are yellow, oval-shaped and occur in clusters of about 20, usually on the undersides of leaves.