The climate baseline: what changed 2010–2026
Environment and Climate Change Canada's data for Metro Vancouver (YVR station baseline) from 2010–2026 vs 1990–2009 shows: mean winter minimum temperature up 1.4°C; days below 0°C reduced by approximately 18 per year; mean summer maximum temperature up 0.8°C; June 2021 heat dome produced 49.6°C in Lytton (new Canadian record) and 40.7°C at YVR. Total annual precipitation broadly stable but shifted toward rain versus snow at lower elevations. These changes are the thermal driver of the range shifts documented below.
Roof rat range expansion in Metro Vancouver
The roof rat's northward range expansion in Metro Van is the most documented local pest range shift of the 2010–2026 period. Historically, roof rats concentrated south of the Fraser and in Vancouver's west side. BCSPCA wildlife records and our own inspection data show a clear northward range extension: consistent roof rat activity in North Vancouver's Lonsdale area from 2019 onward, isolated incidents in Burnaby Heights from 2021, and first documented activity in Coquitlam's Port Moody margin from 2024. The species is not cold-tolerant; the milder winters are directly enabling the expansion.
Brown marmorated stink bug: at Metro Van's doorstep
The brown marmorated stink bug (Halyomorpha halys, BMSB) was first detected in BC in 2019 at Osoyoos, then confirmed established in the Okanagan Valley (Kelowna, Penticton) by 2021–2022. BMSB overwinters in structures — attics, wall voids, warm buildings — in large aggregations. In October–November, populations can invade structures by the hundreds or thousands seeking overwintering sites. Okanagan orchardists have experienced this; it is a serious agricultural pest of tree fruits and vegetables.
BMSB's trajectory from Osoyoos toward Metro Van along the Hope corridor is a matter of time and detection. The species is already established in Washington State south of the 49th parallel, including Bellingham (45 km from Aldergrove). Metro Van detections of individual BMSB specimens have been reported in 2023–2024. A Metro Van establishment event is probable within the 2025–2030 window on current dispersal patterns. The pest management implication: understand the species now so detection and response protocols are ready.
Carpenter ant season extension
Carpenter ant (Camponotus modoc) activity in Metro Vancouver has extended at both ends of the season compared to 1990s baselines. April swarms — rare in the early 2000s — are now documented most years in warmer spring sequences. October carpenter ant worker activity — which would historically have been reduced to dormancy by October cold — is documented with increasing frequency in Metro Van's milder recent autumns. The net effect is approximately 3–4 additional weeks of biological activity at each seasonal end.
Asian giant hornet: the BC eradication story
Asian giant hornets (Vespa mandarinia) were detected at Nanaimo on Vancouver Island in 2019 and at Blaine, Washington in 2019–2022. BC and Washington State jointly mounted an eradication response — destroying all detected nests, including a 2020 Blaine nest that was the first confirmed USNORTHAMERICA breeding colony. The 2022–2023 surveillance seasons detected no new nests; the eradication effort appears to have succeeded in preventing establishment.
The AGH story is the best-case scenario for invasive pest management: early detection through citizen science (multiple nest detections were from homeowner reports), rapid coordinated governmental response, and successful eradication before establishment. It also demonstrates the detection-response capacity that would be needed if BMSB or the next invasive species requires Metro Van-scale response.
Emerald ash borer: the forestry pest approaching BC
The emerald ash borer (Agrilus planipennis) has destroyed billions of ash trees across eastern North America since its US introduction in the early 2000s. It reached Manitoba in 2017 and was detected in Alberta in 2023. BC does not currently have an established EAB population, but the Alberta detection puts it within 3 years of potential BC establishment on current spread rates. Metro Vancouver has significant ash tree populations (Fraxinus spp.) in parks and street trees; an EAB establishment would require a large-scale arboricultural response.
| Species | 2010 status in BC | 2026 status | Metro Van implication |
|---|---|---|---|
| Roof rat (Rattus rattus) | South Van + Vancouver Island only | North Van, parts of Burnaby, expanding | Roofline exclusion critical in North Van |
| Brown marmorated stink bug | Absent | Established Okanagan; approaching Metro Van via Hope | Watch for fall structure invasion |
| Asian giant hornet | Detected Nanaimo, Blaine | Eradicated — no current establishment | Ongoing surveillance needed |
| Emerald ash borer | Absent | Alberta (2023); 3–5 years from potential BC arrival | Street tree monitoring needed |
| Carpenter ant (season length) | April–October active season | Late March–November active season | Earlier prevention work needed |
| European paper wasp (Polistes dominula) | Rare in Metro Van | Increasing establishment in urban Metro Van | Additional wasp species joining standard mix |
What Metro Vancouver residents should monitor
- Brown marmorated stink bug: large shield-shaped insect (1.5 cm), marbled brown upper surface, distinctive geometric pattern. If you find one in your home in October–November, photograph it and report to invasivespeciescouncilbc.ca. If you find multiples — dozens or hundreds in an attic or wall void — you may have a BMSB aggregation event; contact CFIA.
- Asian giant hornet surveillance: if you see a wasp significantly larger than a yellowjacket (4–5 cm body length, yellow head), with an orange-banded abdomen, report immediately to 1-800-STAR-113. Do not disturb.
- Unusual beetles in firewood: if you bring firewood from outside Metro Van (particularly from Alberta, Okanagan, or eastern Canada), inspect it for unusual beetle exit holes or bark galleries before burning indoors. Report any unfamiliar wood-boring beetles.