Dromogomphus spinosus
In 3 days ~10% in a week ~30%
Dromogomphus spinosus, the black-shouldered spinyleg, is a species of dragonflies in the family Gomphidae. Like other spinylegs, D. spinosus have long spines on their legs that help in the capture of prey. True to their name their shoulders are black. The dorsal thorax has a light green I-shaped mark with pale ovals on either side. Their flight time is between late May and early September from southern Manitoba to the east coast of the US as far south as Florida. Terminal segments form a club with yellow lateral markings.
Adults average 2.5 in (64 mm). Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Congaree National Park | 🇺🇸 United States | |
| 2 | Shenandoah National Park | 🇺🇸 United States | |
| 3 | Great Smoky Mountains National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Boston | 🇺🇸 United States | |
| 2 | Montreal | 🇨🇦 Canada | |
| 3 | Dallas | 🇺🇸 United States | |
| 4 | Washington | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Black-Shouldered Spinyleg sighting in Shenandoah National Park on a given day, based on 8 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 571st most-seen of the 723 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
June and August–September
In those months about 10% of wildlife watchers report a Black-Shouldered Spinyleg in Shenandoah National Park on a given day, against under 5% in July and October–May, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Black-Shouldered Spinyleg sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 3
Of the 3 parks where we can rate Black-Shouldered Spinyleg sightings, Shenandoah National Park ranks 2nd at under 5%. The best odds are in Congaree National Park (United States, about 20%).
GBIF citizen-science records
It is estimated from how often the Black-Shouldered Spinyleg is recorded against all the insects logged in Shenandoah National Park (8 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
