I need a safe killer for sawflies
Every year my hardy hibiscus get covered with sawfly larvae and they end up looking horrible. One year I used Systemic stuff and it was great but it's highly toxic, from what I understand.
We get a lot of hummingbirds, especially around my hibiscus and I don't want to poison them. Is there anything safe that I can use to kill the sawflies? Are there any safe but effective systemic products? Or do systemic chemicals not leach into the plant's nectar?
I don't want to use beneficial insects because I don't want them getting into my butterfly garden and killing the caterpillars.