Home Grown 272 September 22, 2004

What is going on in a wooded area around my home? There are hundreds of white caterpillars feeding on the leaves some of some kind of shrubs. What are they and what should I do? I keep reading about new insects from other parts of the world; is this something new?

Sorry to disappoint but this is one of our "made in America" insects. This muncher is called a Dogwood Sawfly. They don't grow up to be a moth or a butterfly. They became a sawfly. You are seeing the larval or juvenile stage that eats and eats. They are around every late summer and fall but this year's population has been huge. If you look at them very carefully, they appear to be coated in powdered sugar or cornstarch that could be rubbed off. Under the dusting of white is a yellow-green body with black spots. If you had one in a glass jar and could see its underside, that color is visible. When these larvae rest, they curl into a "C" shape. Eventually, they loose their frosting and the yellow-green with black spots becomes visible. The bad news is that there is a big crowd this year. The really good news is that they may be eating leaves but it's the end of the season. Most of these shrubs would be loosing leaves in a few weeks anyway. They don't eat the buds for next year. Once the larvae grow as big as they are going to get, they leave the plants and look for some kind of rotted wood lying on the ground to get into to pupate. Failing to find that, occasionally, they attempt to get into composition wood siding or clapboard siding. This could be a problem. This definitely calls for termination with extreme prejudice. For the shrubs, you can use a registered insecticide like Sevin to spray them if they are eating important shrubs. Watch the siding for damage and be prepared to act if you see them causing damage. Of more concern is the fact that we haven't had rain in a number of weeks. Drought stressed shrubs are going to have trouble recovering and setting buds. Water your favorites to protect them.


I'm noticing moss growing in my lawn and in between patio bricks. I went to a local feed and garden store and they told me to dump lime on it because my soil is acidic. This is the first year I've had moss happen this much. Is my soil getting more acidic?

There are two possible reasons for someone to give you this answer. They truly haven't got a clue or they have several pallets of bagged lime in the back they want to unload before winter. Neither one is a good reason to buy lime. Here's why moss appears. It could be that the area is shaded and the grass gave up and dropped dead. Mother Nature hates an empty spot so moss volunteers. It could be that the soil is compacted. If you have a heavier soil like clay, this happens easily. Grass dies; moss happens. It could be that the area doesn't have very good drainage. Because we had so much rain earlier this year, moss could have gotten its toes in the door, especially between patio bricks. It could be that the soil is acidic, but look at the other reasons first. Grass tolerates a wide range of soil pH conditions. Get a soil test to find out about the pH and any nutrient deficiencies. For the patio, you can buy moss-killing products. Since moss is a mega-primitive plant, regular weed killers don't work. Check some of your local stores that carry gardening supplies. You will probably have to rake it out of the lawn to get rid of it. If shade is the problem, moss will probably return to the lawn. Or you could do nothing. The best part of moss is that it never gets tall enough to mow.

Gretchen Voyle, MSU Extension-Livingston County Horticulture
Agent 517/546-3950

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