Iris Borer
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Iris Borer  Iris borer adults are moths with dark brown forewings and yellowish hind wings; wingspan is 2in(5cm). They emerge in summer and lay eggs. The eggs overwinter on old leaves and hatch in April or early May. The larvae are fat pinkish borers up to 2in(5cm) long with brown heads a light stripe down the back, and rows of black dots up the sides. They enter the leaves, feed for several weeks, then pupate in the soil near rhizomes. Iris borers are found in the eastern United States west to Iowa, and in eastern Ontario and Quebec. Susceptible Plants- Iris especially bearded types. Symptoms- Leaves may show irregular tunnels under the leaf surfaces. The iris borer larvae enter a fan of leaves at the top and tunnel down toward the rhizome, where they may eat the whole interior without being noticed.Iris borers often introduce soft rot bacteria into the rhizomes as they feed, causing a wet, slimy, smelly rot.
Prevention and Control- In fall remove dead dry leaves which often carry Iris borer eggs, and destroy badly infested fans in the spring. You can also crush iris borers in the leaves by pinching toward the base of the tell-tale ragged edged leaves, squashing any Iris borers you find. Check rhizomes when you divide the divide the clumps for this pest. If you find a few borers, try cutting them out. Destroy badly infested rhizomes.
Biological Control- Beneficial Nematodes are a natural option to help control some boring insects. These nematodes are microscopic worms that seek out and kill the iris borer caterpillars by introducing a bacteria. Research results using nematodes have been inconsistent, although they can potentially be effective in reducing iris borer populations. Two species of nematodes are commercially available from natural garden supply catalogs or your local garden center. Both species (Heterorhabditis and Steinernema) have been shown to attack iris borer. Nematodes need a moist environment to survive and move. The easiest time to apply is during a rain shower. Lacking rain, water iris before and after applying nematodes. Apply nematodes when iris leaves are almost fully expanded but before flowering. . Pesticide Control- Monterey Garden can be used on outdoor ornamentals, lawns, vegetables and fruit trees and on fire ant mounds. Monterey Garden Insect Spray contains Spinosad, derived through fermentation of a naturally-occurring soil bacterium. Spinosad controls caterpillars, thrips, codling moth, leafminers, borers, fruit flies, fire ants, and more! Spinosad works on the insect’s nervous system, causing paralysis and then death in 1-2 days
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