Northern pine weevils generally do not cause the same amount of damage as pales weevils to branches of conifers.
Northern Pine Weevil
Northern pine weevil larvae pupate in a "chip cocoon" much like the pales and white pine weevils.
Species: Pissodes approximatus Hopkins
Eastern North America from Nova Scotia, Canada to Florida and west to Wisconsin.
Adults feed on foliage of pines, spruce and Douglas-fir; larvae feed on freshly dead pines, occasionally other conifers.
This weevil is not as destructive as the pales weevil and white pine weevil. Northern pine weevils do not strip off tree bark like pales weevils and very high populations are needed in order to cause flagging. Generally, the puncture feeding wounds cause scattered pitch flows. Small seedlings may be killed from feeding by several adults
Description and Life Cycle:
Northern pine weevils look like white pine weevils but breed in the same places as pales weevils. Adult weevils are about 1/4-inch long, and brown with white spots on the wing covers. The adults also have the typical weevil snout. The larvae are white, C-shaped grubs with no legs and brown head capsules.
In Pennsylvania, Ohio and New York, this pest usually overwinters in the adult stage hiding in the duff. Larvae and pupae may also overwinter in dead wood. In April, the adults feed on the branches and pine stumps remaining from the previous falls' cuttings. The weevils mate and females chew a hole into the bark of fresh dead wood in which to lay an egg. The eggs hatch in a week or two, depending on temperature, and the larvae burrow to the cambium layer to start feeding. Larval feeding continues until mid-July and the mature larvae chew into the sapwood to make pupation cells called chip cocoons. The chip cocoons are about 1/4-inch long and are lined with straw-like sawdust. The adults begin to emerge in mid-August. New adults feed on living branches and leaders by making small punctures through the bark, they do not strip off the bark like pales weevils. Feeding is usually limited to the lower branches. The weevils are active at night and on overcast days. They tend to enter hibernation by late October.
Northern pine weevils rarely warrant special controls. Since they are usually associated with pales weevils, control of pales weevils (see No. 252) results in adequate control of the northern pine weevils.
Option 1: Cultural Control - Eliminate Breeding Areas - Since the females lay eggs in freshly dead pine wood such as stumps, cut ends and discarded trees, elimination of this refuse will eliminate breeding sites. Stumps can be pulled out and burned along with other tree remains. This must be done by July, before the new adults begin to emerge.
Option 2: Cultural Control - Isolate Stumps - Cover stumps from the previous year's harvest with plastic or a mound of soil. This will effectively keep the weevils from finding the stumps for oviposition. After one year the wood will no longer be suitable for weevil breeding.
Option 3: Chemical Control - Spring Stump Sprays - Treat stumps which remain from the previous fall tree cutting with registered pesticides in kerosene or fuel oil. Stump treatments should be applied in March through April or when daytime temperatures average 60F. Two to four ounces of spray should be applied to each stump and the surrounding one to two inches of duff.
Option 4: Chemical Control - Summer and Fall Foliage Sprays - If stump treatments were not applied in the spring, foliar sprays may be necessary in August and September. Apply sprays so as to thoroughly cover the lower branches of the trees and any newly planted seedlings.