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FishNovice101

Saw Fly Larvae on pines

18 posts in this topic

Every spring I dread the appearance of the SawFly Larvae. I grew up around pines, but is was not until about 4-5 years ago that I found these nasty little worms on our pine trees in Andover. Nothing seems to take care of them.

Has anyone had any experience with these? Any luck getting rid of them?

Thanks

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My weakness in the area of arboriculture is entomology. I can't really suggest a way treat the trees.

One thing I do know is that as soon as you see an infested tree, removed asap and dispose of the wood.

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I searched on "pine sawfly treatment" and found this from Ohio State.

Control Hints

Best controls are obtained when the larvae are still small, so look for the straw-like needles left behind by the young larvae. Inspections should be made in late April and early May. The egg laying scars can also be seen by inspecting the needles in late winter.

European Pine Sawfly

Strategy 1: Natural Controls - Several parasites have been introduced to control this pest and native birds feed on the larvae. Rodents often eat the pupae in the soil. These agents are usually not adequate in urban settings.

Strategy 2: Mechanical Control, Egg Removal - If the needles containing overwintered eggs can be found before they hatch, they can be pulled off the plants and destroyed. Do not simply through on the ground since the eggs can still hatch.

Strategy 3: Mechanical Control - Colonies of larvae can be easily removed by clipping off the infested branch. Place these branches in a plastic bag and destroy. Colonies can also be knocked off by sharply striking the infested branch. Crush the larvae or knock into a pail of soapy water. If few colonies are present, they can be controlled using these methods but large infestations are better controlled by general spraying.

Strategy 4: Biorational Insecticide Sprays - Several horticultural oils (often called "summer" or "verdant" oils) and insecticidal soaps are labeled for control of sawflies on ornamentals. These usually work well when the sawfly larvae are small and thorough coverage of the colony can be achieved.

Strategy 5: Spot Sprays of Insecticides - Many aerosol or hose end sprayable insecticides are available for spraying of colonies. This is usually adequate for most home landscapes. Nurserymen and Christmas tree growers often carry a small hand pump sprayer with an insecticide mixed for spot treating colonies. See Bulletin 504 for a listing of currently registered insecticides.

Strategy 6: General Insecticide Spraying This sawfly rarely infests large acreages unless controls have not been used for several seasons. General sprays may be warranted if more than 25% of the trees are infested. See Bulletin 504 for a list of currently registered insecticides.

Or check out

http://www.entomology.umn.edu/cues/Web/128EuropeanPineSawfly.pdf

Is that the critter?

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Quetico - I like your response. We having been talking about getting rid of the trees for a few years.

We have sprayed them - with no success. We have 9 pine trees, and they are all infected pretty heavily with them.

It's pretty gross when you come outside in the morning and your vehicle is covered with worms. Yuck!!

Thanks for the advice

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We would always get the little buggers too. Usually only the new growth on our balsem/fir trees seemed to get eaten, the tougher older needles were left alone. If I remember right, we used a product called "Sevin" and would spray the new growth on the trees with it. I think that some fruit tree sprays may also contain it.

Good Luck

Brian

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I had the problem with European Sawflies on my norway pines last spring. We have 18 on our property that are maybe 25 years old. Maybe 3 or 4 of them had the problem. My understanding is that they lay the eggs in the fall and they will hatch in mid to late spring. A tree isn't necessarily infected for good. If you get rid of them and prevent them from laying their eggs, it should be okaynext year.

I used Sevin last year also for the lower 1/3 of the branches. I used a water blast to remove larvae from the middle 1/3 of the branches. Couldn't reach the top 1/3 where I wanted to.

If you have smaller trees, there is a granular insecticide you can apply late in the fall that will be taken up by the tree, Bayer Advanced Garden Tree & Shrub Insect Control. In the spring, the eggs will hatch and the larvae are poisoned when they go to eat the needles. Cost me like $50 though just for 2 trees, so not a great option for larger older trees. Guess I'll see if it does the trick for the two trees I tried it on. I'm also hoping that maybe the cold weather we had this winter eliminated some of them, it got down to -34 at my house once.

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I've been fighting them with Sevin for the last couple of years, and it kills 'em for sure. Last year we had fewer, and according to the bug lady at the DNR, if I'm thorough enough I may be able to eliminate them over time. I sure hope so, because the trees are getting to the point that its hard to reach the upper branches with my garden sprayer.

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Sevin?!? You guys are hardcore. That's some nasty stuff.

The good news is that sawfly larvae are easy to kill, the bad news is they are usually a perennial problem because its nearly impossible to get them all and anyone who's dealt with insects knows it only takes one to make 100.

I think we used talstar or something as simple as horticultural oil.

A general insecticide will work on them. For my mugho pines I just hit them with dish soap and water and spray them off the plan with the hose. I rarely have a lot of damage.

If you've got tall trees or a major problem, consider hiring a tree service that has the tree spraying equipment. With the right gun and the pressure it wan not problem to hit the tops of 80ft trees. Anyone who does that service should have a Commercial Pesticide Applicators license.

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Good point about the Sevin. I used it last year, and then REALLY read the label. Not sure I'll put it on again this year. Probably just blast em off the branches early in the year with a pressure washer. Thought I had read somewhere that they do not usually climb all the way back into the tree?

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For those who don't know if you have sawflies or are looking for them, they are usually hard to spot until you find damage and even then they can be tricky. If you're seeing areas where the worms have eaten needles down to their bases, float your hand close over the top of the branch and watch for movement.

There are usually 3-4 worms eating a single pine needle and they rear back on the hind end to display. You'll see the whole branch "move" because the worms move. Then you know if you' have them or not. They don't move quickly so it should be easy to find them.

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Has anyone seen these show up yet? I checked over the weekend to see if the larvae had hatched on my norway pines. Looked a few low branches over closely and didn't see anything. I'm wondering if they died over the winter since it was so cold? Probably being overly optimistic, it's only May 12th and maybe they haven't hatched yet.

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I'm watching carefully too. The nasty things appear as the new growth shoots get to full extension.

The sprayer is ready.

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Okay thanks. I'm just being optimistic in thinking they died. The new growth shoots are still growing, so guess I'll have to wait.

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Not to burst your bubble but I found them today on my mugho pines. I took some pics but they didn't turn out very well.

The larvae are about 1/2 cm long right now. I laid it on my pinky fingernail for comparison but that pic isn't great either.

They are there for sure.

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I now honestly think a lot of these saw flies died this winter. My thermometer read -34 F one morning at our house. I've been checking my norway pines very closely and have yet to see one even though the new growth is well on it's way. Last year they were very thick by mid to late May.

Venturing into the trails nearby in the norway pines plantation, I see some of them feeding away. But only on the lowest brances in the most central part of the trees. Those on the outside must have been less protected and had 100% mortality.

Anyone in Andover (I'm west of you in Ramsey) see any saw flies this spring?

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My trees in Forest Lake are clean. For now, I'm crediting the judicious application of Sevin during prior infestations.

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are these what you are talking about? I had these last year, but they didn't stay aroung for long. Now they are back again this year.

June2008047.jpg

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Thats what they are TKO. I seen them all over today here in East Bethel.

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