CrustaceansIn Hamilton County, Ohio
Common Pill Woodlouse
Armadillidium vulgare (Latreille, 1804)
Common Pill Woodlouse in all of Ohio- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Malacostraca
- Order
- Isopoda
- Family
- Armadillidiidae
- Genus
- Armadillidium
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)
Near Hamilton County
Range
Where it is recorded
Season shown in 1 of Ohio's 88 counties. Explore Ohio
- No result yet (33)
- Recorded, too few records for a result (48)
- Recorded, season not shown (6)
- Season shown (1)
Counties as a table
| County | Records |
|---|---|
| Adams County | No qualifying records yet |
| Allen County | Recorded, too few records for a result |
| Ashland County | Recorded, too few records for a result |
| Ashtabula County | Recorded, too few records for a result |
| Athens County | Recorded, too few records for a result |
| Auglaize County | No qualifying records yet |
| Belmont County | Recorded, too few records for a result |
| Brown County | No qualifying records yet |
| Butler County | 45 · Recorded, season not shown |
| Carroll County | No qualifying records yet |
| 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 | 55 · Recorded, season not shown |
| Darke County | Recorded, too few records for a result |
| Defiance County | No qualifying records yet |
| Delaware County | 25 · Recorded, season not shown |
| Erie County | Recorded, too few records for a result |
| Fairfield County | Recorded, too few records for a result |
| Fayette County | No qualifying records yet |
| Franklin County | 77 · 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 | 33 · Recorded, season not shown |
| Hancock County | Recorded, too few records for a result |
| Hardin County | Recorded, too few records for a result |
| Harrison County | No qualifying records yet |
| Henry County | No qualifying records yet |
| Highland County | No qualifying records yet |
| Hocking County | No qualifying records yet |
| Holmes County | No qualifying records yet |
| Huron County | Recorded, too few records for a result |
| Jackson County | No qualifying records yet |
| Jefferson County | Recorded, too few records for a result |
| Knox County | Recorded, too few records for a result |
| 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 | No qualifying records yet |
| Muskingum County | Recorded, too few records for a result |
| Noble County | No qualifying records yet |
| 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 | No qualifying records yet |
| Putnam County | No qualifying records yet |
| Richland County | Recorded, too few records for a result |
| Ross County | No qualifying records yet |
| Sandusky County | Recorded, too few records for a result |
| Scioto County | No qualifying records yet |
| Seneca County | No qualifying records yet |
| Shelby County | No qualifying records yet |
| Stark County | 28 · Recorded, season not shown |
| Summit County | 48 · Season shown |
| Trumbull County | Recorded, too few records for a result |
| Tuscarawas County | No qualifying records yet |
| Union County | Recorded, too few records for a result |
| Van Wert County | No qualifying records yet |
| Vinton County | No qualifying records yet |
| Warren County | Recorded, too few records for a result |
| Washington County | No qualifying records yet |
| 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 Hamilton County
Not enough evidence
The weeks are still too uncertain to show a season. Based on 33 records in 9 of the 10 years from 2016 to 2025, above the minimum of 20 records from 5 different years.
Show over the bars
Records per week from 33 records in 9 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 Common Pill Woodlouse | Years recorded | Records of all species |
|---|---|---|---|
| Jan 4–10 | 0 | 0 | 392 |
| Jan 11–17 | 0 | 0 | 344 |
| Jan 18–24 | 0 | 0 | 312 |
| Jan 25–31 | 0 | 0 | 206 |
| Feb 1–7 | 0 | 0 | 357 |
| Feb 8–14 | 0 | 0 | 383 |
| Feb 15–21 | 0 | 0 | 366 |
| Feb 22–28 | 0 | 0 | 391 |
| Mar 1–7 | 0 | 0 | 551 |
| Mar 8–14 | 1 | 1 | 523 |
| Mar 15–21 | 0 | 0 | 750 |
| Mar 22–28 | 0 | 0 | 1,012 |
| Mar 29 – Apr 4 | 0 | 0 | 1,535 |
| Apr 5–11 | 0 | 0 | 1,960 |
| Apr 12–18 | 1 | 1 | 2,492 |
| Apr 19–25 | 0 | 0 | 2,403 |
| Apr 26 – May 2 | 0 | 0 | 3,783 |
| May 3–9 | 2 | 2 | 3,307 |
| May 10–16 | 1 | 1 | 2,059 |
| May 17–23 | 0 | 0 | 2,153 |
| May 24–30 | 2 | 2 | 2,390 |
| May 31 – Jun 6 | 1 | 1 | 2,648 |
| Jun 7–13 | 0 | 0 | 2,715 |
| Jun 14–20 | 5 | 5 | 2,695 |
| Jun 21–27 | 6 | 5 | 2,714 |
| Jun 28 – Jul 4 | 1 | 1 | 3,220 |
| Jul 5–11 | 4 | 2 | 2,980 |
| Jul 12–18 | 1 | 1 | 3,031 |
| Jul 19–25 | 2 | 2 | 2,961 |
| Jul 26 – Aug 1 | 1 | 1 | 2,795 |
| Aug 2–8 | 0 | 0 | 2,884 |
| Aug 9–15 | 0 | 0 | 2,696 |
| Aug 16–22 | 0 | 0 | 2,535 |
| Aug 23–29 | 0 | 0 | 2,536 |
| Aug 30 – Sep 5 | 2 | 2 | 2,606 |
| Sep 6–12 | 0 | 0 | 2,980 |
| Sep 13–19 | 1 | 1 | 2,959 |
| Sep 20–26 | 0 | 0 | 2,313 |
| Sep 27 – Oct 3 | 0 | 0 | 2,122 |
| Oct 4–10 | 0 | 0 | 1,828 |
| Oct 11–17 | 0 | 0 | 1,793 |
| Oct 18–24 | 0 | 0 | 1,338 |
| Oct 25–31 | 0 | 0 | 1,023 |
| Nov 1–7 | 1 | 1 | 676 |
| Nov 8–14 | 0 | 0 | 593 |
| Nov 15–21 | 1 | 1 | 384 |
| Nov 22–28 | 0 | 0 | 496 |
| Nov 29 – Dec 5 | 0 | 0 | 356 |
| Dec 6–12 | 0 | 0 | 478 |
| Dec 13–19 | 0 | 0 | 285 |
| Dec 20–26 | 0 | 0 | 322 |
| Dec 27 – Jan 2 | 0 | 0 | 388 |
In Ohio
Late March to late October, middle week Jun 14–20
Middle week · Jun 14–20
This week · Nov 8–14
Show over the bars
Records per week from 678 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 464 dates. Latest record: December 2025.
Show as a table
| Week | Records of Common Pill Woodlouse | Years recorded | Records of all species |
|---|---|---|---|
| Jan 4–10 | 0 | 0 | 6,211 |
| Jan 11–17 | 1 | 1 | 5,146 |
| Jan 18–24 | 1 | 1 | 4,645 |
| Jan 25–31 | 1 | 1 | 4,698 |
| Feb 1–7 | 0 | 0 | 6,023 |
| Feb 8–14 | 0 | 0 | 5,888 |
| Feb 15–21 | 1 | 1 | 5,436 |
| Feb 22–28 | 2 | 2 | 6,846 |
| Mar 1–7 | 2 | 2 | 8,321 |
| Mar 8–14 | 7 | 4 | 10,384 |
| Mar 15–21 | 11 | 3 | 12,620 |
| Mar 22–28 | 9 | 5 | 13,949 |
| Mar 29 – Apr 4 | 6 | 3 | 19,661 |
| Apr 5–11 | 16 | 5 | 26,860 |
| Apr 12–18 | 16 | 5 | 39,925 |
| Apr 19–25 | 18 | 8 | 41,623 |
| Apr 26 – May 2 | 36 | 8 | 56,391 |
| May 3–9 | 50 | 8 | 52,952 |
| May 10–16 | 35 | 8 | 53,785 |
| May 17–23 | 48 | 8 | 57,698 |
| May 24–30 | 35 | 8 | 54,651 |
| May 31 – Jun 6 | 20 | 6 | 53,099 |
| Jun 7–13 | 16 | 6 | 53,700 |
| Jun 14–20 | 32 | 8 | 56,625 |
| Jun 21–27 | 29 | 9 | 55,361 |
| Jun 28 – Jul 4 | 27 | 9 | 58,477 |
| Jul 5–11 | 20 | 6 | 61,336 |
| Jul 12–18 | 17 | 5 | 64,722 |
| Jul 19–25 | 14 | 5 | 69,753 |
| Jul 26 – Aug 1 | 20 | 6 | 59,416 |
| Aug 2–8 | 7 | 2 | 59,712 |
| Aug 9–15 | 10 | 5 | 55,994 |
| Aug 16–22 | 9 | 6 | 54,328 |
| Aug 23–29 | 15 | 5 | 51,772 |
| Aug 30 – Sep 5 | 17 | 7 | 57,167 |
| Sep 6–12 | 15 | 7 | 59,075 |
| Sep 13–19 | 12 | 6 | 54,543 |
| Sep 20–26 | 15 | 5 | 45,860 |
| Sep 27 – Oct 3 | 11 | 4 | 43,180 |
| Oct 4–10 | 13 | 5 | 37,841 |
| Oct 11–17 | 12 | 5 | 30,824 |
| Oct 18–24 | 4 | 2 | 21,156 |
| Oct 25–31 | 16 | 6 | 19,021 |
| Nov 1–7 | 7 | 3 | 14,172 |
| Nov 8–14 | 7 | 4 | 12,621 |
| Nov 15–21 | 4 | 3 | 7,965 |
| Nov 22–28 | 3 | 3 | 8,136 |
| Nov 29 – Dec 5 | 3 | 2 | 6,083 |
| Dec 6–12 | 1 | 1 | 6,004 |
| Dec 13–19 | 1 | 1 | 5,423 |
| Dec 20–26 | 3 | 1 | 5,661 |
| Dec 27 – Jan 2 | 3 | 1 | 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
Look-alikes
Land cover
Often confused with
- Nosy Pill Woodlouse Armadillidium nasatumOften confused in Ohio: 122 identifications in Ohio named one where the other was meant
- Rathke's Woodlouse Trachelipus rathkiiOften confused in Ohio: 37 identifications in Ohio named one where the other was meant
- Common Shiny Woodlouse Oniscus asellusOften confused in Ohio: 30 identifications in Ohio named one where the other was meant
- Common Rough Woodlouse Porcellio scaberOften confused in Ohio: 12 identifications in Ohio named one where the other was meant
- Common Striped Woodlouse Philoscia muscorum267 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 | 96%49% |
| Forest | 2%31% |
| Farmland | 1%11% |
| Wetland | 0.5%5% |
| Open water | 0.2%3% |
From 418 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)
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
678 records from 2 datasets.
- iNaturalist Research-grade Observations (opens in a new tab) · iNaturalist.org · 676 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.
- iNaturalist observations (opens in a new tab) · iNaturalist.org · 2 recordsiNaturalist. Available from https://www.inaturalist.org. Accessed 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.