Hello,

It's too late to apply an insecticide against white pine weevil, Pissodes strobi  (Coleoptera: Curculionidae),  Early to mid-April is the best time to make this application.  See below.

The white pine weevil is known to attack many species of pine and spruce, and occasionally Douglas-fir, but white pine is the preferred host.  The adult weevils overwinter in the litter and emerge very early (first few warm days) in the spring to lay eggs.  Eggs are laid in small punctures chewed in the bark and hatch into small, legless grubs in about a week.  Larval feeding on the inner bark girdles the leader which causes the characteristic "shepard's hook" appearance of the leader.  A heavy attack will eventually kill the leader.  Larvae construct pupal chambers under the bark of the leader, and line them with fine shavings of wood and inner bark. White pine adults feed on the inner bark by chewing small holes through the outer bark.

Cultural control involves pruning leader below the area where larvae are feeding before July.  When you prune out the infested leader, make sure not to leave the cut terminals lying in the field because the larvae will continue to develop. After the dead leader is removed, select a healthy lateral shoot on the uppermost whorl to become the new leader. Trim the rest of the shoots back to one-half of their original length. This will enable the tree to recover its apical dominance and good form faster. Damage from white pine weevil can be prevented by spraying the upper terminals of spruce and pine next year in early to mid-April and again two weeks later.

Recommended material include cyfluthrin (sold as Bayer Advanced Yard and Garden Spray), when the adults first emerge from leaf litter in early to mid-April.  Cyfluthrin has been shown to be highly effective against white pine weevil in Christmas tree plantations.  Professional applicators may use Tempo (cyfluthrin). Timing of the application is critical.  The trees should be inspected every 2 or 3 days as the weather warms for the presence of the adult weevils on the leaders, in the lake states this normally occurs when suppertime temperatures first break the 50 °F mark.

Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.

See recent articles with pictures about white pine weevil in the MSU CAT Alerts at: http://news.msue.msu.edu/news/article/white_pine_weevil_damage_on_conifers_is_causing_wilted_leaders

 https://www.canr.msu.edu/news/control_white_pine_weevil_in_early_spring