Nosy Pill Woodlouse
Armadillidium nasatum Budde-Lund, 1885
Nosy Pill Woodlouse in all of Ohio- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Malacostraca
- Order
- Isopoda
Introduced and invasive status
Introduced in Ohio: iNaturalist (opens in a new tab)
Also listed
- Introduced in the lower 48 states
iNaturalist's volunteer curators list it as introduced in their Ohio checklist.
Status: Simpson A, Sellers E, Pagad S (2023). United States Register of Introduced and Invasive Species (US-RIIS), ver. 2.0. U.S. Geological Survey, https://doi.org/10.5066/P9KFFTOD (opens in a new tab)
Range
Where it is recorded
Season shown in 0 of Ohio's 88 counties. Explore Ohio
- No result yet (24)
- Recorded, too few records for a result (57)
- Recorded, season not shown (7)
- Season shown (0)
Counties as a table
| County | Records |
|---|---|
| Adams County | No qualifying records yet |
| Allen County | No qualifying records yet |
| Ashland County | Recorded, too few records for a result |
| Ashtabula County | Recorded, too few records for a result |
| Athens County | 42 · Recorded, season not shown |
| Auglaize County | No qualifying records yet |
| Belmont County | Recorded, too few records for a result |
| Brown County | Recorded, too few records for a result |
| Butler County | 117 · Recorded, season not shown |
| Carroll County | Recorded, too few records for a result |
| Champaign County | Recorded, too few records for a result |
| Clark County | Recorded, too few records for a result |
| Clermont County | Recorded, too few records for a result |
| Clinton County | Recorded, too few records for a result |
| Columbiana County | Recorded, too few records for a result |
| Coshocton County | Recorded, too few records for a result |
| Crawford County | Recorded, too few records for a result |
| Cuyahoga County | 34 · Recorded, season not shown |
| Darke County | Recorded, too few records for a result |
| Defiance County | No qualifying records yet |
| Delaware County | 27 · Recorded, season not shown |
| Erie County | Recorded, too few records for a result |
| Fairfield County | Recorded, too few records for a result |
| Fayette County | Recorded, too few records for a result |
| Franklin County | 96 · Recorded, season not shown |
| Fulton County | No qualifying records yet |
| Gallia County | Recorded, too few records for a result |
| Geauga County | Recorded, too few records for a result |
| Greene County | Recorded, too few records for a result |
| Guernsey County | No qualifying records yet |
| Hamilton County | 64 · Recorded, season not shown |
| Hancock County | Recorded, too few records for a result |
| Hardin County | No qualifying records yet |
| Harrison County | Recorded, too few records for a result |
| Henry County | No qualifying records yet |
| Highland County | Recorded, too few records for a result |
| Hocking County | Recorded, too few records for a result |
| Holmes County | No qualifying records yet |
| Huron County | No qualifying records yet |
| Jackson County | No qualifying records yet |
| Jefferson County | No qualifying records yet |
| Knox County | No qualifying records yet |
| Lake County | Recorded, too few records for a result |
| Lawrence County | No qualifying records yet |
| Licking County | Recorded, too few records for a result |
| Logan County | No qualifying records yet |
| Lorain County | Recorded, too few records for a result |
| Lucas County | Recorded, too few records for a result |
| Madison County | Recorded, too few records for a result |
| Mahoning County | Recorded, too few records for a result |
| Marion County | Recorded, too few records for a result |
| Medina County | Recorded, too few records for a result |
| Meigs County | Recorded, too few records for a result |
| Mercer County | No qualifying records yet |
| Miami County | Recorded, too few records for a result |
| Monroe County | No qualifying records yet |
| Montgomery County | Recorded, too few records for a result |
| Morgan County | No qualifying records yet |
| Morrow County | Recorded, too few records for a result |
| Muskingum County | Recorded, too few records for a result |
| Noble County | Recorded, too few records for a result |
| Ottawa County | Recorded, too few records for a result |
| Paulding County | Recorded, too few records for a result |
| Perry County | No qualifying records yet |
| Pickaway County | Recorded, too few records for a result |
| Pike County | Recorded, too few records for a result |
| Portage County | Recorded, too few records for a result |
| Preble County | Recorded, too few records for a result |
| Putnam County | No qualifying records yet |
| Richland County | Recorded, too few records for a result |
| Ross County | Recorded, too few records for a result |
| Sandusky County | Recorded, too few records for a result |
| Scioto County | Recorded, too few records for a result |
| Seneca County | Recorded, too few records for a result |
| Shelby County | No qualifying records yet |
| Stark County | Recorded, too few records for a result |
| Summit County | 22 · Recorded, season not shown |
| Trumbull County | No qualifying records yet |
| Tuscarawas County | Recorded, too few records for a result |
| Union County | Recorded, too few records for a result |
| Van Wert County | No qualifying records yet |
| Vinton County | Recorded, too few records for a result |
| Warren County | Recorded, too few records for a result |
| Washington County | Recorded, too few records for a result |
| Wayne County | Recorded, too few records for a result |
| Williams County | Recorded, too few records for a result |
| Wood County | Recorded, too few records for a result |
| Wyandot County | No qualifying records yet |
No mapped range from the range source used, the USGS Gap Analysis Project, which maps land vertebrates only.
Season
When it is recorded
In Franklin County
Late August to early November, middle week mid-October
Recorded in two separate seasons, each shown with its own early, middle and late weeks. An earlier season is not shown: most records are from one year.
Records per week from 96 records in 8 of the 10 years from 2016 to 2025. Shows when people recorded it, not a season or how common it is.
Show as a table
| Week | Records of Nosy Pill Woodlouse | Years recorded | Records of all species |
|---|---|---|---|
| Jan 4–10 | 0 | 0 | 417 |
| Jan 11–17 | 0 | 0 | 236 |
| Jan 18–24 | 0 | 0 | 236 |
| Jan 25–31 | 0 | 0 | 236 |
| Feb 1–7 | 1 | 1 | 244 |
| Feb 8–14 | 0 | 0 | 360 |
| Feb 15–21 | 0 | 0 | 270 |
| Feb 22–28 | 0 | 0 | 401 |
| Mar 1–7 | 0 | 0 | 483 |
| Mar 8–14 | 0 | 0 | 567 |
| Mar 15–21 | 2 | 2 | 561 |
| Mar 22–28 | 0 | 0 | 750 |
| Mar 29 – Apr 4 | 2 | 1 | 1,310 |
| Apr 5–11 | 2 | 2 | 1,456 |
| Apr 12–18 | 1 | 1 | 2,408 |
| Apr 19–25 | 2 | 2 | 2,525 |
| Apr 26 – May 2 | 22 | 4 | 2,812 |
| May 3–9 | 5 | 3 | 2,785 |
| May 10–16 | 2 | 2 | 2,381 |
| May 17–23 | 2 | 1 | 2,651 |
| May 24–30 | 6 | 3 | 2,735 |
| May 31 – Jun 6 | 3 | 2 | 2,861 |
| Jun 7–13 | 1 | 1 | 2,986 |
| Jun 14–20 | 3 | 1 | 2,980 |
| Jun 21–27 | 1 | 1 | 3,051 |
| Jun 28 – Jul 4 | 3 | 2 | 3,121 |
| Jul 5–11 | 3 | 3 | 3,399 |
| Jul 12–18 | 0 | 0 | 3,754 |
| Jul 19–25 | 0 | 0 | 3,305 |
| Jul 26 – Aug 1 | 0 | 0 | 3,347 |
| Aug 2–8 | 0 | 0 | 3,803 |
| Aug 9–15 | 1 | 1 | 3,507 |
| Aug 16–22 | 0 | 0 | 3,137 |
| Aug 23–29 | 3 | 2 | 3,249 |
| Aug 30 – Sep 5 | 1 | 1 | 3,487 |
| Sep 6–12 | 1 | 1 | 3,215 |
| Sep 13–19 | 1 | 1 | 3,368 |
| Sep 20–26 | 3 | 3 | 2,586 |
| Sep 27 – Oct 3 | 1 | 1 | 3,624 |
| Oct 4–10 | 6 | 4 | 2,701 |
| Oct 11–17 | 7 | 3 | 2,107 |
| Oct 18–24 | 2 | 2 | 1,201 |
| Oct 25–31 | 0 | 0 | 1,123 |
| Nov 1–7 | 4 | 3 | 789 |
| Nov 8–14 | 4 | 2 | 798 |
| Nov 15–21 | 0 | 0 | 468 |
| Nov 22–28 | 1 | 1 | 522 |
| Nov 29 – Dec 5 | 0 | 0 | 225 |
| Dec 6–12 | 0 | 0 | 234 |
| Dec 13–19 | 0 | 0 | 392 |
| Dec 20–26 | 0 | 0 | 254 |
| Dec 27 – Jan 2 | 0 | 0 | 422 |
In Ohio
Late March to mid-November, middle week Jun 14–20
Records per week from 829 records in 10 of the 10 years from 2016 to 2025. Shows when people recorded it, not how common it is. The grey bars show how many records of all species were made here each week, so you can see when recording itself was high or low; the season is not adjusted by them.
Recorded on 549 dates. Latest record: December 2025.
Show as a table
| Week | Records of Nosy Pill Woodlouse | Years recorded | Records of all species |
|---|---|---|---|
| Jan 4–10 | 2 | 1 | 6,211 |
| Jan 11–17 | 1 | 1 | 5,146 |
| Jan 18–24 | 0 | 0 | 4,645 |
| Jan 25–31 | 0 | 0 | 4,698 |
| Feb 1–7 | 2 | 2 | 6,023 |
| Feb 8–14 | 1 | 1 | 5,888 |
| Feb 15–21 | 8 | 3 | 5,436 |
| Feb 22–28 | 2 | 2 | 6,846 |
| Mar 1–7 | 7 | 4 | 8,321 |
| Mar 8–14 | 6 | 5 | 10,384 |
| Mar 15–21 | 11 | 4 | 12,620 |
| Mar 22–28 | 9 | 5 | 13,949 |
| Mar 29 – Apr 4 | 11 | 5 | 19,661 |
| Apr 5–11 | 20 | 7 | 26,860 |
| Apr 12–18 | 17 | 7 | 39,925 |
| Apr 19–25 | 34 | 8 | 41,623 |
| Apr 26 – May 2 | 50 | 6 | 56,391 |
| May 3–9 | 62 | 8 | 52,952 |
| May 10–16 | 40 | 8 | 53,785 |
| May 17–23 | 40 | 8 | 57,698 |
| May 24–30 | 36 | 6 | 54,651 |
| May 31 – Jun 6 | 23 | 8 | 53,099 |
| Jun 7–13 | 18 | 7 | 53,700 |
| Jun 14–20 | 23 | 6 | 56,625 |
| Jun 21–27 | 31 | 7 | 55,361 |
| Jun 28 – Jul 4 | 22 | 9 | 58,477 |
| Jul 5–11 | 21 | 7 | 61,336 |
| Jul 12–18 | 10 | 5 | 64,722 |
| Jul 19–25 | 11 | 4 | 69,753 |
| Jul 26 – Aug 1 | 9 | 4 | 59,416 |
| Aug 2–8 | 5 | 3 | 59,712 |
| Aug 9–15 | 13 | 4 | 55,994 |
| Aug 16–22 | 9 | 5 | 54,328 |
| Aug 23–29 | 10 | 5 | 51,772 |
| Aug 30 – Sep 5 | 16 | 7 | 57,167 |
| Sep 6–12 | 19 | 8 | 59,075 |
| Sep 13–19 | 17 | 8 | 54,543 |
| Sep 20–26 | 15 | 8 | 45,860 |
| Sep 27 – Oct 3 | 21 | 6 | 43,180 |
| Oct 4–10 | 24 | 8 | 37,841 |
| Oct 11–17 | 39 | 7 | 30,824 |
| Oct 18–24 | 15 | 7 | 21,156 |
| Oct 25–31 | 18 | 5 | 19,021 |
| Nov 1–7 | 15 | 6 | 14,172 |
| Nov 8–14 | 20 | 4 | 12,621 |
| Nov 15–21 | 13 | 4 | 7,965 |
| Nov 22–28 | 5 | 2 | 8,136 |
| Nov 29 – Dec 5 | 7 | 5 | 6,083 |
| Dec 6–12 | 2 | 2 | 6,004 |
| Dec 13–19 | 0 | 0 | 5,423 |
| Dec 20–26 | 6 | 3 | 5,661 |
| Dec 27 – Jan 2 | 13 | 4 | 8,459 |
What these results show
These results show when people recorded a species, not when or where it occurs. Missing weeks and low counts do not mean absence or scarcity, and counts are not abundance. Contributed records reflect where, when and what people chose to observe.
Identification
How to identify it
Often confused with
- Common Pill Woodlouse Armadillidium vulgareOften confused in Ohio: 122 identifications in Ohio named one where the other was meant
- Rathke's Woodlouse Trachelipus rathkiiOften confused in Ohio: 36 identifications in Ohio named one where the other was meant
- Common Rough Woodlouse Porcellio scaberOften confused in Ohio: 25 identifications in Ohio named one where the other was meant
- Common Shiny Woodlouse Oniscus asellusOften confused in Ohio: 19 identifications in Ohio named one where the other was meant
- Common Striped Woodlouse Philoscia muscorum66 identifications worldwide named one where the other was meant
From iNaturalist’s similar-species counts, refreshed monthly: confusions in Ohio first, then worldwide. Only species with an Ohio result are listed.
Land cover where it is recorded
| Land cover | Its recordsAll Ohio records |
|---|---|
| Developed | 84%49% |
| Forest | 11%31% |
| Farmland | 4%11% |
| Grassland and shrub | 0.4%0.9% |
| Barren | 0.2%0.6% |
| Open water | 0.2%3% |
| Wetland | 0.2%5% |
From 514 records placed within 100 m, beside all Ohio records placed the same way. People record where they go, so this shows where records come from, not where the species lives. Land cover: USGS Annual NLCD, 2025 (opens in a new tab)
Finer identifications
Some Ohio records of this species were identified to a subspecies:
- Armadillidium nasatum nasatumsubspecies
Every one of these records counts toward the Nosy Pill Woodlouse's season above.
Why some records go further than species
Many species vary from place to place. Groups of a species that look or sound a little different, and live in different areas, can be named as subspecies. Observers and experts only identify a record that far when it shows enough detail to tell them apart. Records without that detail count at the species level.
Names: Catalogue of Life.
Sources
Where these results come from
- Records from iNaturalist research-grade observations and expert-identified GBIF datasets, CC0, CC BY and CC BY-NC. Sources
- Seasons use the published method and its evidence thresholds. Methods
- See it on iNaturalist (opens in a new tab)OpenPhenology is independent and not affiliated with iNaturalist.
Records behind the Ohio result
829 records from 1 dataset.
- iNaturalist Research-grade Observations (opens in a new tab) · iNaturalist.org · 829 recordsiNaturalist contributors, iNaturalist (2026). iNaturalist Research-grade Observations. iNaturalist.org. Occurrence dataset https://doi.org/10.15468/ab3s5x accessed via GBIF.org on 2026-11-13.
To cite: the GBIF download doi:10.15468/dl.y2jkt8 (opens in a new tab).
A spreadsheet (CSV) with a link to each record, on iNaturalist or GBIF. Records whose location was hidden by the observer or the source are counted but not linked.