Irises: When do borer moths hatch?, 1 by robicho

robicho wrote:
Here in eastern Ontario, Canada USDA zone 4b-5, they emerge out of the soil around mid-September. I do a thorough garden cleaning in mid-October to make sure I get rid of all eggs in the debris then place the lot in the garbage, NOT the compost pile! What was missed, if any, then hatches and starts chewing their way into the new fans around the same time as the Daffodils are in bloom.

Around the last week of May, I check fans very closely for chew marks. If present, I squeeze/pinch between my forefinger and thumb along the fan from the top to the bottom until I hear it 'POP'. It can be quite a job if you have hundreds of Iris but the cleaner the beds are both spring and fall, the chance of borer damage are decreased considerably.

The photo attached is of a mature fella on July 30, 2007 when we were relocating the beds.