I'm copying my post I'd just made in the other thread about iris borers. In summary, spinosad-based sprays seem to work for me.

As a follow-up to my earlier post (June 21 2016), I'm pleased to say that after having dug up about a third of my irises and looking at the rest of them, I have not had any iris borers this year. Can't say for sure that it was due to the one time spinosad spray I'd applied back in April but you can be sure I'll use it again next Spring!

Most chemical treatments are banned in Nova Scotia so that is not a route open to me. The squish to destroy and beheading is my option. I wish they hung out an occupied sign so I could find them easier

I am curious about the spinosad stuff to see if anyone else has used it with success. I sounds less toxic than imidacloprid. Anyone else used it? Results?

I use a form of it for potato beetles.......if I remember correctly, it's .05%, in the product I use. here's some info:
http://www.ipm.ucdavis.edu/TOO...

Marry Anne, It's worth checking out if Nova Scotia does indeed ban spinosad. It's actually semi-organic as it is derived from a bacterium found in the soil. It has relative low toxicity and as a precaution for bees, it should be applied in the evening so that it no longer has effect by the next day when bees become active again. It's safe enough that it can be used on vegetable plants.

I just looked and spinosad is approved for use in Nova Scotia. Check it out at:

http://www.novascotia.ca/nse/p...

Wow! Thank you so much for checking that out, Ivor. I am amazed. I never checked since so many chemicals were removed from our stores and banned from use unless one is a commercial grower. Now I need to go back and see what people said about using it and where I can purchase it. Thanks again. Folks on this forum are fabulous!!

You can also try nemtodes if you prefer no chemicals. We are still on the find & squish mode.

Well, so much for the spinosad use. It is a product not sold in Canada based on the research I have done online. Some people have ordered it in from US resources but in US $ and significant costs for shipping if you can get it past customs. I am not willing to go that route so back to squish and behead!! I know of a source for nemtodes so I think I will try that first next spring. The only issue is my irises are spread out over several perennial beds so I doubt I could treat them all. Thanks to all for the info on the iris borer.

Is "BT" available in Canada ?
http://pestcontrol.domyownpest...

it DOES work for iris borers, although you need to re apply often, and early...so you catch them before they are too far down into the fan. Test results I have seen don't rate it "very high", as to borer control, but, it would be better than nothing

I found two borers in my Mayan Mystery today while digging, and I treated. Guess I didn't get that area well enough. Two rhizomes were completely destroyed.

Yes, I get BT. I use it when necessary on the cabbages. To work though, my understanding is it needs to contact the borer. Is that correct? If so, I will not likely have much luck because I never see them. They must hatch and move very quickly for cover!!

Yes, the borer has to come in "contact" with it.....that's why it's not as effective as the systemic poisons. Still, it does help...a little ! I use it on the iris that are grown next to "edibles', and on the re bloomers, when (if) they rebloom. I never see honey bees on spring bloom irises....I guess there are too many other things they would rather harvest....so I use the 'Merit" products in the spring, on them, but, late season blooms will attract the bees....so, I use the BT. I apply every week.....and try to get the solution to run down "into" the fan......probably not the best thing for rot prevention, but I haven't seen that soft rot is apparent in those sprayed that way .
You also have to spray "early", before they are into the rhizomes....so you need to start just as bloom is ready to end. That's the "good thing" about the systemics....no matter where he is, he'll get a dose.

I have used some poisons in the past but I cannot do it due to the Wren family that made a nest in the nest box I put out right next to the iri's. They have babies now and I see the parents looking for whatever they eat in and among the iris so I just am checking them by hand. I found signs of the borers on one iris I have all by itself. It is done blooming and I cut off the stalks and noticed the jagged edges and slime. I cut the leaves, but no borers inside. I waited to late to check. Oh well. They can't get them all, can they? Last year I found 3 in one rhizome of one lily and tossed it.

I put down systemics very early this season and found that I have had fewer borers. Most are near bushes or evergreen trees. The moths tend to hide in those and they are not very high flyers. I only treated twice but very early in the season. They say the hatching starts after two consecutive days of 70 degree weather. If you get them while they are very small, they are goners but spraying after they are inside the leaves does not do much.