Small black flies coating undersides of Cornus Stoloniferae

Augh! I cannot get rid of these things - just sprayed "Trounce" without joy, or confidence that this will get rid of the thousands of small black flies that have focused on a row of Cornus shrubs.

Any ideas how this happened? I don't feel like I'm able to get the "Trounce" everywhere it should go. I escalated to this when plain Safer soap didn't do the trick. I prefer green/eco-benign solutions as do most of us.


This invasion is on the heels of aphids running roughshod over other shrubs, caterpillars in my "Monch" Asters and something that leaves thousands of tiny brownish clots on my Purple Dome" ones.

Is anyone else in BC having this kind of summer - so discouraging for a newbie gardener that so many of my new plantings are having bug troubles...

If anyone knows of a strictly "green" person/company that could help with these shrubs, I'm all ears!

 

If they're actual flies and not aphids then they may be just roosting on the shrubs, and liable to soon disappear on their own.

 

I don't think they're benign, Ron, as there is a lot of leaf discoloration after they inhabit for awhile - droopy, bruised purple looking leaves, and other discoloration on leaves deep into the shrubs where it's hard for me to get a good look.

Could be something else is afoot with the Cornus, and the flies are just attracted to a stressed plant? Here is where being ignorant, and only having my mom's pesticide-mad 1970s books to hand gets really frustrating.

BTW, thanks for your help on my Chaenomeles "Cameo" - it's much happier with less direct spray from the sprinkler system our predecessors in this house installed.

I will watch carefully and see what happens with the flies. If there's more discoloration, shoud I just trim out those branches that are affected? I have three shrubs of this type, and they are all affected.

Thanks kindly for your help...

 

You have to get an idea what they are and if they are in fact damaging the shrubs before being able to take effective (or at least sensible) measures. Try a good local garden center, where somebody shown the leaves and bugs in a bag might know what they are.

 

Just went out and checked my one aster...and it too is well populated with greenish/yellow caterpillers munching away...and also dropping their little blackish poops all over the foliage.

At the end of September, my strategy with these would be the same as with the cornus flies...try to ignore them. The asters are in full bloom right now, and will be mush in a month or so with the constant rain and colder nights, I don't figure the caterpillers will make much of a dent in them in the grand scheme.

I don't have c. stolonifera now, but remember trying to kill one that took over too much of the garden years back...they are vigorous plants...took several years chopping it right to ground level to finally exit that specimen. So, I'd consider just living with the flies unless the foliage gets noticeably ugly. The purplish colour is also going to happen this time of year anyway...the leaves on my c. florida are quite purplish along with much yellow, they are probably thinking of autumn and beginning to senesce.

Your preference for eco friendly solutions is wonderful. The upside to living with some pests (as you probably know) is they will tend to attract predators that bring them more into balance...but this only happens if we encourage each other to be patient...so I'll ignore the caterpillers on your aster if you ignore them on mine :-)