Please, look at the pictures of one twig of my Mountain ash. Found this link: http://www.pricelandscaping.ca/lawn-care-services.php Looks like mine is infested with the Mountain Ash Sawfly. Besides cutting infested leaves, are there any chemicals to kill larvae on the rest of the tree (I did not see any until today I found these worms eating the leaves on one twig). The tree was planted in the ground this June. Thank you!
See this thread for discussion re: management, though note that there was a misidentification corrected now that I've read your post. Chemical treatment would seem to be overkill when they are easily plucked off and killed in a bath of water.
Will look through the suggested thread. Thank you. Re: chemicals - I meant to kill the eggs (will inspect all the leaves tomorrow, maybe will be able to see eggs in them). If I find new larvae tomorrow, will collect them and drown them in a bucket of water... I wonder how those flies found my tree...
From Snohomish County in 2009 to here in 5 years, so they get around. I would suspect there being some sort of chemical signal they are picking up on. The eggs are small, but noticeable -- they are laid in geometric clusters.
Bought this tree at a Pitt Meadows nursery (they only sell the trees, the grower was from Surrey). Not sure if I may name both nurseries here. BTW, the former mislabeled the tree as Aucuparia while it is Americana... I saw some black wasp like looking insect sitting on a rose next to the mountain ash. Thought it was a wasp, now I know it was this nasty fly... Can't control every pest in my big garden... Fungi and pests have been driven me really mad since I got this first garden in my life 2 years ago... Will look for eggs in leaves tomorrow.