What is Pine Sawfly? (and could it affect my trees?)

//What is Pine Sawfly? (and could it affect my trees?)

What is Pine Sawfly? (and could it affect my trees?)

What is Pine Sawfly?

Evergreen sawflies, in general, are caterpillar-like, sawfly larvae and usually prove common springtime pests. Several species feed on the needles of evergreen trees in groups and can cause extensive defoliation in some years. The adult sawfly is a stingless wasp that causes no harm. Light populations may not cause serious damage, but moderate to heavy populations can significantly impact tree health over entire areas of pine-predominant forestation.

Pine sawfly larvae in particular are white or pale-yellow caterpillar like worms that hatch from eggs laid by female adults in rows on pine tree needles.


what is Pine Sawfly? could it affect my trees? read more on ArborScape Denver Tree Service blog



Newly hatched larvae voraciously feed on the needles and can defoliate a tree completely in a matter of days if the infestation is large enough and left untreated.

According to the Colorado State Forest Service, the pine sawfly outbreak in Elbert County that received significant media attention in 2014 is predicted to again result in heavy needle loss in some local pine stands this summer, based on a report released today by the CSFS. This report indicates that while many ponderosa pine stands in the county will suffer little to no sawfly defoliation this year, others likely will suffer another season of moderate to heavy defoliation.

This projected outbreak will most likely have the greatest effect on

  • Parker

  • Elizabeth

  • Franktown

  • Castle Rock

  • and points East-Southeast



what is Pine Sawfly? could it affect my trees? read more on ArborScape Denver Tree Service blog




Over the next few weeks, regularly check your pine trees for the white worm-like caterpillars on the ground at the base of the tree and on the needles towards the ends of the branches where new needle growth has formed. Look closely- but a large infestation is hard to miss if you are standing close to the tree.

If you believe that you may have a sawfly infestation, please contact ArborScape for a fast, free tree care evaluation with a variety of treatment options.

Chemical controls and spray applications to actively feeding larvae are effective and can help stop defoliation if applied soon after feeding has begun. Complete coverage is important for control, so it’s important to use a professional plant health care company for this work.


Get your free tree care evaluation here
or call us to schedule at 303-806-TREE !



Additional pine sawfly resources

USDA Forest Service overview:

CSU Extension overview:

Douglas County Extension Office:

Elbert County Extension Office:


last modified

Jun 6, 2017 @ 2:26 pm


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