 Rutgers Cooperative Extension With increasing temperatures, it is plausible that a critical treatment window for controlling White Pine Weevil (WPW) will be present early next week, throughout many areas of NJ. Factors leading to this post include increased air temperatures and climbing growing degree-days (WPW adult movement and egg laying is around 7-58 growing degree-days (GDD50)), and most importantly rising soil temperatures as this pest typically begins movement with soils hovering around 50F. All of these factors lead to the possibility of WPW movement early next week and growers may wish to utilize a preventative, long lasting residual spray (pyrethroids) to target adults before they begin egg laying.
So we have:
- NJ will be within the GDD window for adult movement and approaching egg laying (7-58 GDD50)
- Soil temperatures in some areas may be close to 50F.
- Increased air temperatures and insect mobility
| White Pine Weevil (Pissodes strobi) – potential for emergence as of 3/6/2026 |
| Region |
Location |
CODE |
METRIC |
FRI |
SAT |
SUN |
MON |
TUES |
WEDS |
| 6-Mar |
7-Mar |
8-Mar |
9-Mar |
10-Mar |
11-Mar |
| Southern |
Upper Deerfield |
NJ50 |
GDD50 |
0 |
0 |
9 |
13 |
18 |
31 |
| High Temp [ºF] (Average) |
49 (43.5) |
52 (50.5) |
63 (52) |
67 (45) |
71 (62) |
71 (60.5) |
| 24hr Average – Soil TEMP [ºF] |
47.1 |
<- (This will change over time / no prediction available) |
| Central |
Freehold / Howell |
NJ50 |
GDD50 |
0 |
0 |
4 |
6 |
9 |
17 |
| High Temp [ºF] (Average) |
42(39) |
49(48) |
62(51.5) |
69(56.5) |
74(63) |
70(59) |
| 24hr Average – Soil TEMP [ºF] |
40.7 |
<- (This will change over time / no prediction available) |
| Northern |
HACKETTSTOWN |
G5633 |
GDD50 |
0 |
0 |
3 |
3 |
6 |
17 |
| High Temp [ºF] (Average) |
41(37.5) |
47(45.5) |
61(49.5) |
69(55) |
76(63) |
68(55) |
| 24hr Average – Soil TEMP [ºF] |
34.1 |
<- (This will change over time / no prediction available) |
| USPEST.ORG – Model: simple average/growing degree-day, Min: 50F – Max: 95F, NMME forecast |
| Forecast: 7-month NMME based seasonal climate forecast (USPEST.ORG) – Subject to change regularly = Check Often |
| Air temperatures: Weather Underground (https://www.wunderground.com/) and NEWA: (https://newa.cornell.edu/) |
| Soil temperatures (10cm): https://www.greencastonline.com/tools/soil-temperature |
| Compiled by Waller. T. 3/6/2026 [twaller@njaes.rutgers.edu] |
In the state of NJ, the control window against feeding white pine weevil adults *typically* occurs in March & April. Adults over-winter in the duff beneath trees. The adults will often crawl or sometimes fly to the top terminal leaders of pine, spruce, or Douglas-fir trees. Eastern white pine & Norway spruce species are the most severely attacked & the death of the terminal leaders of these trees will often occur.
Treatment timing is critical with this pest and controlling the adult female before egg laying is necessary. Apply preventative sprays (e.g., pyrethroids) only to the terminal leaders during this time. Before mating & egg laying, adults will feed by chewing holes within the central leader & cause a characteristic pitch flow that becomes white in color when dry. Then females will lay eggs in new cut-out holes within the top 12 inches of the leader just below the terminal bud.
Chemical Controls:
Chemical insecticides against white pine weevils during the spring period are only effective when adults are feeding & before females lay eggs. Arial sprays only need to be applied to cover the terminal leaders at the tops of trees. Pyrethroids sprayed on the bark can have an effective residual of up to 3-weeks. Included within this group of insecticides include bifenthrin (e.g., Onyx), permethrin (e.g., Astro) & cyfluthrin (e.g., Tempo). Since an extended egg-laying duration occurs with this pest, a second application may be recommended.
When given enough time, a preventative systemic such as imidacloprid (e.g., Merit) can be applied as a soil injection or drench during the previous fall season (October or November) to control the early spring feeding period of adults. It can also be effective against the early instar larvae. This approach may only be economically viable when a few select trees can be targeted having a history of this pest.
Overall, the best integrated controls are achieved with a combination of well timed insecticide treatments against spring feeding adults & the mechanical removal of infested terminal leaders before summer adult emergence occurs.
^Adapted from this excellent resource written by Steve Rettke: click here – “White Pine Weevil: Overwintering Adults Become Active in March & April”
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