spinosad for sawfly/roseslug - success
Last year I posted here about a significant problem I was having with my roses: the leaves would end up lacy, brown, skeletonized and the plant would eventually defoliate, although I would never see any visible insects. Several people pointed to the rose sawfly or roseslug larvae as the likely culprit. It wasn't at all uniform - different roses had remarkably different susceptibility to this pest, the most vulnerable being "William Baffin".
This year as soon as the damage began to appear I did a single application of Spinosad in May(this was before any flowers had appeared so no bees were around). It stopped the damage in its tracks; I left one plant unsprayed as a control and it is now almost leafless.
So, can others add their opinions? Does this pest(s) breeze through in the spring and then disappear for the year making second applications unnecessary? Would you recommend other alternatives (hort oil, soap?) as equally effective?