Managing Spring Pests on Evergreens

Look for small, white, woolly tufts or masses on the twigs of hemlock (Tsuga canadensis) (Photos: Julie Holmes, CFIA). Right now is the BEST time to scout for Hemlock Woolly Adelgid (Adelges tsugae) because of the visibility of the egg masses.  It is not a common pest in Ontario, in fact it has been found at only one site in Etobicoke and in the Niagara gorge area.  Unfortunately it is a common pest in the neighbouring US.

J. Holmes - Eggs and adult DSCN4090                                                          These small, white, woolly masses contain the tiny eggs that give rise to the next generation of hemlock woolly adelgid (Photo magnified: Julie Holmes, CFIA).  This is a regulated pest by the Canadian Food Inspection Agency and should be reported to CFIA if it is detected here.  Infested trees are removed and destroyed in an effort to protect our beautiful hemlock trees.

PineBarkAdelgid                              PINE BARK ADELGID damage was evident on white pine last years. These adelgids feed by sucking plant sap out of twigs stems.

PineBarkAdelEggsMagnifiedMH                                                          Right now, pine bark adelgis egg masses (see above, Photo: LO Nursery Scout Melissa Huntley) and nymphs are present on white pines (Pinus strobus), and Pinus contorta. Egg masses are covered in white, woolly wax and are found near buds. Once eggs hatch, an application of insecticide (Malathion, Orthene, Tristar) may be warranted where populations are high. Check out the factsheet from Michigan State University for some excellent photos: (

Balsam twig aphid stem mother on swollen bud. (Photo credit: Rayanne Lehman, Penn. Dept. of Ag.,

Monitor for overwintering Balsam twig aphid eggs on terminal buds on fir, white spruce, Colorado spruce and juniper, they are susceptible to dormant oil applications.

                                                                          Eggs will be hatching in the coming weeks and developing into stem mothers (nymphs). The tiny, bluish grey aphid stem mothers can be found on terminal buds as they break.

                                                          Tap twigs over a black surface to easily see teeny-tiny BTA stem mothers.  Apply Diazinon, Malathion and Tristar on warm days (55 to 78 GDD Base 10oC OR before bud caps loosen off) to target these stem mothers and prevent the damaging generation that follows.

<a href="/clm/species/pissodes_spp"><em>Pissodes sp.</em></a> (White Pine Weevil) adult. 

Overwintering white pine weevil adults are active and are laying eggs on last year’s leader of pine and spruce, when the Forsythia starts to bloom. Monitor for small black/brown snout beetles around the foliage and in the duff layer below the canopy. An application of insecticide on last year’s leader may help reduce successful egg-laying and damage to this year’s leader.

DCEastSprGallOWFem                                                    Cooley spruce gall adelgid and Eastern spruce gall adelgid overwintering females have already started laying their eggs and are no longer susceptible to insecticides. Use a pin to push away the woolly masses covering the female bodies to see the tiny brown eggs.  If no eggs are found, just dark adelgid nymph bodies…….they are still susceptible to insecticides.

<a href="/clm/species/oligonychus_ununguis"><em>Oligonychus ununguis</em></a> (Spruce Spider Mite) eggs.                              Monitor for eggs of spruce spider mite on conifers with a history of mite damage (Abies, Picea, Thuja). Spruce spider mite eggs appear as very tiny, round, reddish-brown spheres that adhere to the UNDERSIDES of twigs and foliage this time of year. YOU WILL REQUIRE A HAND LANDS TO SEE THEM CLEARLY. Monitor lower branches, on the North and Eastern side of the tree, this is where most of the feeding damage is done. These eggs are susceptible to dormant hort oil applications in the next few weeks, where temperatures permit and plant species are not sensitive.  Miticides will be effective once eggs hatch to nymphs, usually around bud break and early foliar emergence (Floramite, Kanemite, Vendex).

Pine shoot beetle adults have emerged. The tiny beetles take flight after 2-3 days where temperatures reach 10-12oC (Photos: Ed Czerwinski) . Adults lay eggs underneath the bark of stressed or dead pine trees and stumps. Those larvae will develop later in April and May. Remove brood material (i.e. trap (sentinel) logs, snags, dead/dying trees) before new progeny adults emerge (210 GDD, Base 10C) to comply with the CFIA. All brood material must be burned, chipped (less than 2cm diameter) or buried (30 cm deep) to comply with CFIA standards.


About Jen Llewellyn

OMAFRA Nursery and Landscape Specialist @onnurserycrops
This entry was posted in Insects, Uncategorized and tagged , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s