Multi-colored Asian lady beetle in fruit crops
Rufus Isaacs, Small Fruit Extension Specialist, Department of Entomology, Michigan State University

NEW fall 2005: Update for grape growers (view pdf file)

Background 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. Raspberry, blackberry, grape, and peach are particularly affected. At left, a multi-colored Asian lady beetle searches for prey on a blooming pear tree.

R. Isaacs

Identification 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 the 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 regular- to irregularly-shaped "M" if viewed from the front, or "W" if viewed from behind. (Pictured at left to show an "M") 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 the fall.

Immatures (larvae) are covered with tiny, flexible spines that do not sting. (See photo at right of larva 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. Damage Fruit growers and MSU Extension agents first reported direct feeding damage by adult Asian lady beetles in Michigan during fall 2001. The greatest number of reports was from fall raspberries and on over-ripe grapes in the southern half of the Lower Peninsula, though the beetle is present through much of Michigan. It is still unclear whether the beetles are starting this damage or whether they are exploiting berries that have already been split for other reasons. Either way, their presence is most unwelcome at harvest.

Photo: Tyler Fox

A more serious issue for growers selling fresh berries is the potential for contamination with adult Asian lady beetles. If berries are picked with beetles and then placed in cold storage, the beetles seem to move away from the cold, and this typically means that they burrow deeper into the berry. Once out on the fruit stand, beetles may warm up and fly out of the container, but they could also be bought and eaten.

When disturbed, the adults release a noxious yellow-orange liquid from their legs. This is called reflex bleeding and is meant to prevent birds and other predators from eating the beetle. The defense secretion is extremely bitter and unpleasant tasting with a strong odor. Preventing beetles from being harvested is important to avoid contamination that can lead to customer complaints and off-flavors in juice or wine. Learning more about the biology of the Asian lady beetle can help in understanding how to prevent their infestation into a fruit planting, and this is briefly reviewed below.

Biology
The multi-colored Asian lady beetle is similar to native lady beetles in many ways. It also feeds on soft-bodied insects such as aphids and leafhoppers. However, some of its habits are different from those of native species. To find out more, including how to distinguish the introduced species from our native lady beetles, visit our web page about biology.

Management
Growers that find their fruit infested with a few adult beetles immediately before picking can instruct hand pickers to carefully avoid them. This may not be economically feasible on a large planting, however, and growers may have to resort to other tactics. Camphor and menthol have recently been shown to repel adult beetles, but their activity lasted for only a short time and no commercial formulations are yet available.

Ladybeetles are efficient predators of pest insects for the majority of the growing season, and most chemical controls for this introduced beetle will also kill native predators. If beetles reach pest levels in a fruit planting before harvest, insecticides applied for other near-harvest pests may allow growers to achieve insect-free fruit during harvest. Pesticides applied for control of other beetle pests such as Japanese beetle are likely to control Asian lady beetle infestations. The waiting period restrictions will vary by crop, so the labels should be checked carefully before any product is used near to harvest, to allow pickers to re-enter and harvest to proceed.

Pesticides should be applied only to infested areas to minimize chemical exposure and to avoid causing outbreaks of other plant-infesting pests because these products also kill beneficial insects. Many pesticides are labeled for use only by certified, licensed applicators that have received specialized training on the use and disposal of pesticides. These pesticides should not be applied by unlicensed homeowners, and at all times, their use should be in accordance with the label.

Information cards about Asian lady beetle for distribution to U-Pick customers and others
We created information cards with color photos and a brief summary of the information offered at this web site. The cards are no longer available, but you may click here to see a pdf file of the card and its contents. Similar information is available in this pdf file of an article that may be copied in newsletters (click here).