The Q&A Archives: Crabapple and Beetles

Question: I went out to cut my grass today only 1 week after cutting it before and noticed the leaves on my crab apple tree were all red and burnt looking. I thought it was heat damage until I got closer and saw a ton of beetles on each leaf of the tree. There was nothing left but red dry veins on the leaves that they had already munched on. Is there anything I can do for my tree? or is it doomed to die? Please let me know. This is my first home and its a new construction so I planted the trees when we moved in. I thought it would be around to grow with my kids. Thanks.

Answer: I don't think all is lost, but you certainly have a fight on your hands! Both adult and immature Japanese beetles are highly destructive pests. Adults emerge in July and August and feed on the foliage and fruit of hundreds of species of plants, often skeletonizing the leaves and gouging the fruit. The beetles are 1/3 to 5/8 inch long with a metallic green body and bronze outer wings. They have several small tufts of white hairs along the sides of the abdomen and a prominent pair of tufts near the tip. Females intermittently stop feeding to lay eggs in buried 2 to 6 inches deep in soil.

The eggs hatch by midsummer. Larvae, which are among the many kinds of ?white grubs? found in lawns and pastures, feed in the roots of grasses and other plants. Japanese beetle grubs are the most widespread turf-grass pest in the United States. They pass the winter buried in soil and complete their development in late Spring.

The insecticide carbaryl (Sevin) is very effective against the adult beetles. However, repeated use of Sevin will cause mite populations to explode (which can cause other problems in your garden). Because of this, it is best to leave the adult beetles alone in most cases. Traps may be used to suppress Japanese beetles, but the traps must be placed at least 30 feet away from the plants to be protected. The traps will draw in adult beetles. If the trap is too close to the plant to be protected, the beetles may stop and feed for a while before entering the trap.

Milky spore disease is a bacterial disease that kills Japanese beetle grubs. Spores of this bacterium are produced commercially and sold under the names of Doom,, Japidemic, and Milky Spore. The application of milky spore may reduce the numbers of Japanese beetle grubs in lawns but beetles will fly in from other areas to damage plants and crops.

Hope this information provides some help!

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