Hammerjawed jumper (Zygoballus rufipes)
The hammerjawed jumper is a spider in the family Salticidae that is not dangerous to people. GBIF holds 348 licensed U.S. records of it; it reaches our listing threshold in 25 states, most of all Texas (89), Pennsylvania (36) and New York (22). Its observation records peak in May.
Zygoballus rufipes, commonly called the hammerjawed jumper, is a species of jumping spider which occurs in the United States, Canada, and Central America. Adult females are 4.3 to 6 mm in body length, while males are 3 to 4 mm.
From Wikipedia: Zygoballus rufipes, text under CC BY-SA 4.0.
Is the hammerjawed jumper poisonous or venomous?
Not in any medically significant way. Like almost all spiders the hammerjawed jumper (family Salticidae) has venom for its prey, but it is not a widow or recluse, the two U.S. groups whose bites need medical attention.
Which states have the hammerjawed jumper?
Records are spread over 25 states; the top three, Texas, Pennsylvania and New York, hold 42% of them.
| # | State | Records | Share of state spiders | Rank in state |
|---|---|---|---|---|
| 1 | Texas | 89 | 0.3% | 67th of 386 |
| 2 | Pennsylvania | 36 | 0.5% | 37th of 164 |
| 3 | New York | 22 | 0.4% | 55th of 149 |
| 4 | Illinois | 21 | 0.1% | 125th of 243 |
| 5 | Virginia | 16 | 0.1% | 93rd of 176 |
| 6 | Massachusetts | 15 | 0.3% | 56th of 189 |
| 7 | Oklahoma | 15 | 0.3% | 67th of 149 |
| 8 | Florida | 14 | 0.1% | 117th of 237 |
| 9 | Indiana | 10 | 0.2% | 85th of 133 |
| 10 | Maryland | 10 | 0.2% | 86th of 153 |
| 11 | New Jersey | 9 | 0.4% | 54th of 127 |
| 12 | Georgia | 8 | 0.1% | 102nd of 186 |
| 13 | Louisiana | 8 | 0.2% | 67th of 107 |
| 14 | Arkansas | 7 | 0.4% | 52nd of 114 |
| 15 | North Carolina | 7 | 0.1% | 100th of 184 |
| 16 | Ohio | 7 | 0.1% | 105th of 332 |
| 17 | Tennessee | 7 | 0.2% | 76th of 138 |
| 18 | West Virginia | 7 | 0.9% | 23rd of 90 |
| 19 | Minnesota | 4 | 0.1% | 90th of 145 |
| 20 | Wisconsin | 4 | 0.1% | 108th of 149 |
| 21 | Kentucky | 3 | 0.2% | 77th of 103 |
| 22 | Missouri | 3 | 0.1% | 76th of 117 |
| 23 | Alabama | 2 | 0.1% | 107th of 143 |
| 24 | Connecticut | 2 | 0.2% | 60th of 86 |
| 25 | Michigan | 2 | 0.1% | 85th of 122 |
When is the hammerjawed jumper seen?
Across the U.S., observation records of the hammerjawed jumper run mostly April through September, peaking in May with 27% of them. Almost none are from December to February.
Where the hammerjawed jumper is recorded in each state
Texas
Texas holds 89 licensed records, the joint 67th most recorded of 386 spiders listed there. Its observation records in Texas run mostly April through August, peaking in April; most licensed records come from Fort Bend County, Erath County and Tarrant County. Next come Travis County (6) and Dallas County (3).
Pennsylvania
Pennsylvania holds 36 licensed records, the joint 37th most recorded of 164 spiders listed there. Most of its licensed records in Pennsylvania come from Allegheny County, Westmoreland County and Bucks County. Next come Philadelphia County (3) and Crawford County (2).
Top counties in the U.S.
| # | County | State | Records | Share of U.S. |
|---|---|---|---|---|
| 1 | Fort Bend County | Texas | 53 | 15.2% |
| 2 | Allegheny County | Pennsylvania | 13 | 3.7% |
| 3 | Erath County | Texas | 10 | 2.9% |
| 4 | Tarrant County | Texas | 8 | 2.3% |
| 5 | Westmoreland County | Pennsylvania | 6 | 1.7% |
| 6 | Travis County | Texas | 6 | 1.7% |
| 7 | Bucks County | Pennsylvania | 5 | 1.4% |
| 8 | Philadelphia County | Pennsylvania | 3 | 0.9% |
| 9 | Dallas County | Texas | 3 | 0.9% |
| 10 | Crawford County | Pennsylvania | 2 | 0.6% |
| 11 | Harris County | Texas | 2 | 0.6% |
| 12 | Butler County | Pennsylvania | 1 | 0.3% |
| 13 | Centre County | Pennsylvania | 1 | 0.3% |
| 14 | Erie County | Pennsylvania | 1 | 0.3% |
| 15 | Lackawanna County | Pennsylvania | 1 | 0.3% |
How recent are the hammerjawed jumper records?
Most of what is known about the hammerjawed jumper is recent: 70% of dated U.S. records were made in 2017–2026, and half date from 2020 or later. The oldest dated record is from 1933; the busiest year was 2011, with 58 records.
| Decade | Records | Share |
|---|---|---|
| 1930s | 4 | 1.1% |
| 1940s | 2 | 0.6% |
| 1960s | 5 | 1.4% |
| 1970s | 2 | 0.6% |
| 1980s | 10 | 2.8% |
| 1990s | 6 | 1.7% |
| 2000s | 8 | 2.3% |
| 2010s | 115 | 32.4% |
| 2020s | 203 | 57.2% |
Species recorded in the same counties
Of the 25 counties where the hammerjawed jumper is most recorded, 17 are also top counties for both the bronze jumper and the familiar jumping spider; no other spider shares more. None of its closest neighbors is venomous.
| Species | Shared counties |
|---|---|
| Bronze jumper | 17 |
| Familiar jumping spider | 17 |
| Bold jumper | 16 |
| Flea jumping spider | 16 |
| Arabesque orbweaver | 15 |
| Nursery web spider | 15 |
| Triangulate bud spider | 15 |
| Black-and-yellow argiope | 14 |
Related species in the U.S.
Other members of the family Salticidae with profiles here: Bold jumper, Familiar jumping spider, Zebra spider, Bronze jumper, Magnolia green jumper and Half-edged wall jumping spider.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.