Insect problem 2

rhodyluverMay 27, 2008

ok, so i found out what my insects are :Lace bugs!

how do i get rid of them?

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rhodyman(SE PA, USDA Z6)

I assume you had a combination of weevils and Lace Bug.

The easiest way to solve the Lace Bug problem is to move the plant into more shade. The insects that prey on Lace Bugs thrive in the shade and become ineffective in the sun. There are certain rhododendrons that are good in the sun which are Lace Bug resistant, and there are others that are not good in the sun which are Lace Bug susceptible.

When I had a registered nursery, I had to kill all lace bugs for my annual inspections, so I would spray with Malathion on the underside of the leaves. Now I don't bother. Spraying actually makes the problem worse in the long run since it kills the natural enemies of the Lace Bugs. I have plants in places where they do well and the small amount of Lace Bug I see will keep the population of natural enemies going.

When you read in a catalog that a certain rhododendron does well in the sun, it usually means that it resistant to Lace Bug. Ones that need partial shade are suspect. It could be sun intolerance or Lace Bug susceptibility. Remember, rhododendrons need several hours of sun each day to form flower buds. I have a couple that bloom in deep shade, but that is the exception. Most need some light, but too much may cause Lace Bug problems.

Here are the details on Lace Bugs:

Rhododendron Lace Bugs, Stephanitis rhododendri, and Azalea Lace Bugs, Stephanitis pyrioides: Adults are about 1/8-inch long. The body is pale yellow. The lacy wings (very distinctive) are held flat over the back and are transparent with two dark spots present. The nymphs are black, spiny and smaller than the adults. The eggs over-winter partially embedded in leaf tissue. The eggs hatch in May. The nymphs mature into adults in June and lay eggs during late June and July. The second generation of nymphs appears in August. The over-wintering eggs will be laid when these nymphs become adults. adults and nymphs feed on the undersides of leaves by piercing the leaves with their mouthparts and sucking the plant juices. This causes a mottled, silvery or white discoloration, known as stippling, on top of the leaf where the chlorophyll has been removed. The undersides of leaves are covered with dark brown to black, sticky spots of excrement. Plant rhododendrons in shade to maximize the activities of beneficial insects.

Here is a link that might be useful: Common Problems and Their Solutions.

    Bookmark   May 27, 2008 at 10:30AM
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aggierose

Rhodyman, you mention beneficial insects that prey on lacebugs, but you never mention what those are. What insects prey on lacebugs?

    Bookmark   May 27, 2008 at 7:05PM
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rhodyman(SE PA, USDA Z6)

Many and not just insects. Natural enemies of lace bugs (predators, parasites, diseases) include assassin bugs, green lacewing larvae, lady beetles, jumping spiders, pirate bugs, predaceous mites, a trichogrammatid wasp, a mymarid wasp, predatory thrips, an insect-killing fungus (Beauveria bassiana), and other diseases.

    Bookmark   May 28, 2008 at 4:28PM
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