Craesus septentrionalis
In 3 days ~10% in a week ~20%
Craesus septentrionalis, the flat-legged tenthred or birch sawfly, is a species of insect in the order Hymenoptera, the suborder Symphyta and the family Tenthredinidae. It was first described by Carl Linnaeus in 1758. The adult sawflies are black and brown with transparent wings and the larvae are yellowish-green and resemble caterpillars. The larvae feed on the leaves of various species of deciduous tree. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 2 | Wadden Sea National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Birmingham | 🇬🇧 United Kingdom | |
| 2 | Helsinki | 🇫🇮 Finland | |
| 3 | Paris | 🇫🇷 France | |
| 4 | Saint Petersburg | 🇷🇺 Russia |
Rare
Under 5% of wildlife watchers report a Hazel Sawfly sighting in Birmingham on a given day, based on 6 verified sightings from GBIF citizen-science data. It is the 668th most-seen of the 811 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
August and September
In those months about 10% of wildlife watchers report a Hazel Sawfly in Birmingham on a given day, against under 5% in October to July, the lowest months.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most Hazel Sawfly sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 4 cities where we can rate Hazel Sawfly sightings, Birmingham has the highest daily chance: under 5%. Next come Helsinki (Finland, under 5%) and Paris (France, under 5%).
Same family: Tenthredinidae
The closest relatives of the Hazel Sawfly that you can see in Birmingham (family Tenthredinidae, Common Sawflies) are Willow Redgall Sawfly (about 10%), Red-Belted Cleaver (about 10%) and Turnip Sawfly (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Hazel Sawfly is recorded against all the insects logged in Birmingham (6 verified sightings), 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.
