The two striped ground spider (Acantholycosa lignaria), also known as the woodlouse spider, is a common spider found throughout the eastern United States. With their distinctive appearance featuring a yellow body and two dark stripes running down the abdomen, two striped ground spiders are a type of wolf spider that lives and hunts on the ground, feeding primarily on insects and other invertebrates. Like many other spiders, the two striped ground spider does possess venom that contains neurotoxic components. However, the venom is not considered medically significant or dangerous to humans.
Are Two Striped Ground Spiders Poisonous?
No, two striped ground spiders are not poisonous to humans. While the venom of Acantholycosa lignaria does contain compounds that are toxic to the nervous systems of insects and other small invertebrates, it does not pose any significant danger to human health. The venom is not potent enough to cause anything beyond minor localized pain and irritation.
Two Striped Ground Spider Venom and Toxicity
All spiders produce venom to subdue and digest prey. Two striped ground spiders primarily prey on insects like crickets, cockroaches, and flies, as well as other spiders and small invertebrates. Their venom contains neurotoxins that disrupt nervous system functioning in these small arthropods, leading to paralysis and death. However, the venom is not medically significant for humans.
Some components in Acantholycosa lignaria venom include:
– Cytotoxins – Compounds that damage cell membranes
– Neurotoxins – Compounds that affect nervous system functioning
– Hyaluronidases – Enzymes that break down tissue connections
– Phospholipases – Enzymes that break down fats
These compounds can be effective at immobilizing and killing small prey insects and spiders but do not have significant toxicity against larger animals with complex nervous systems like humans.
When two striped ground spiders bite humans, it generally results in minor localized reactions like:
– Mild pain
– Redness
– Itching/Irritation
– Swelling
Systemic symptoms beyond the bite site are very rarely observed. No life-threatening symptoms or significant tissue damage has been linked to two striped ground spider bites. The global incidence of confirmed spider envenomation from this species is extremely low.
Venom Apparatus
Two striped ground spiders, like most other spiders, have a venom delivery apparatus called a chelicerae consisting of two hollow fangs. When they bite, the fangs inject venom directly into the wound.
The chelicerae of Acantholycosa lignaria are relatively small compared to spiders with more potent, dangerous venoms. The fangs are only able to penetrate partially into human skin and inject venom quite superficially.
Additionally, two striped ground spiders have much smaller venom glands and deliver significantly less venom overall per bite than more medically significant spider species like black widows. This further limits potential toxicity.
Bite Symptoms
Here are some common symptoms that may be observed following a two striped ground spider bite:
– Mild to moderate pain – Typically lasts for 5-60 minutes
– Redness around the bite site – Diameter usually less than 5 cm
– Itching, tingling, burning sensations – Lasts for a few hours
– Mild swelling/inflammation – Generally resolves within 24 hours
More severe reactions are very uncommon but could potentially include:
– Nausea, abdominal pain – Rare systemic symptoms
– Headache, dizziness – Possible mild neurological effects
– Muscle cramps, tremors – Rare neuromuscular symptoms
– Rash, hives – Allergic response to venom components
Despite some references to necrosis in rare cases, tissue damage has not been verified. Two striped ground spider bites pose no risk of necrotic wounds requiring debridement.
If any concerning neurological or systemic symptoms develop or if signs of infection emerge, medical evaluation is recommended. But most bites result in only minor discomfort resolved within a day or two.
First Aid for Bites
Here are some basic first aid steps for two striped ground spider bites:
– Clean bite site thoroughly with soap and water
– Apply cool compress to reduce pain and swelling
– Monitor for any signs of infection – seek medical care if needed
– Take over-the-counter pain medication as needed
– Avoid scratching or irritating bite to prevent infection
– Elevate limb if bite is on arm or leg
– If systemic symptoms develop, go to emergency room
The bite can be covered with a clean bandage/dressing. Topical antibiotics or antiseptics can be applied if needed. More significant reactions may require steroids or other medications rarely. But most symptoms can be managed with just wound care and over-the-counter pain/anti-itch relief.
Are Bites Life-Threatening?
No, two striped ground spider bites are not considered life-threatening. No records of fatalities or severely medically significant envenomations from this species exist in the medical literature.
Unlike spiders like black widows or brown recluses, two striped ground spiders lack potent neurotoxins or necrotic venom components. Envenomation symptoms beyond minor localized pain and irritation are very uncommon.
In the vast majority of bites, the only symptom is brief moderate pain similar to a bee sting. More severe effects like tissue damage, seizures, respiratory distress, anaphylaxis or systemic toxicity essentially never occur.
Healthy adults are not at any risk of dangerously toxic effects from a two striped ground spider bite. The only individuals potentially at higher risk would be young children or those with compromised immune systems. But even in these cases, bites warrant only basic first aid and monitoring without aggressive treatment.
Overall, two striped ground spider venom does not pose a medically important hazard, and bites should not be considered life-threatening. Prompt medical care for severe symptoms is still advisable though.
Differences from Dangerous Spiders
Two striped ground spiders can be differentiated from more dangerous spider species by several key factors:
1. Appearance – Distinctive striping and non-spherical body shape
2. Size – Only 6-20 mm in body length
3. Habitat – Found on ground not webs; often under rocks/logs
4. Venom – Much less potent neurotoxins and lack necrotic agents
5. Bite effects – Localized, minor reactions predominately
6. No confirmed cases of severe envenoming or death
Some spiders with medically risky venom include:
– Black widows – Neurotoxic, latrodectism syndrome
– Brown recluses – Cytotoxic, necrotic skin lesions
– Hobo spiders – Moderate necrotic potential
– Spider wasps – Extremely painful stings
In contrast, two striped ground spiders have limited toxicity and pose very little risk beyond a briefly painful bite. Lack of confirmed significant envenomations is the most telling factor in their low hazard level for humans.
Preventing Bites
Here are some tips to avoid getting bitten by two striped ground spiders:
– Carefully inspect and shake out clothing, shoes, towels left on floors before use
– Wear gloves and long sleeves when moving rocks, logs, debris where spiders may hide
– Use caution when placing hands in dark crevices and under large objects
– Keep living spaces clean and clutter-free to discourage spider habitation
– Remove trash, vegetation, and food waste from around the home
– Keep screens in good repair to prevent spider entry
– Apply pesticides if large infestations are noted
– Teach children not to touch spiders and to alert adults if any are spotted
While bites are not considered medically significant, taking simple precautions can help prevent painful bites. Non-toxic prevention measures combined with sealing entry points into the home provide the best spider control.
Are They Aggressive or Dangerous to Pets?
Two striped ground spiders are generally not aggressive toward humans or pets. They prefer to avoid confrontation when possible. However, they may bite in self-defense if compressed against skin, handled carelessly, or otherwise provoked.
Pets may be at slightly higher risk of bites, especially curious cats who swat at spiders. But the venom poses no significant danger to mammals like cats, dogs, rodents, or livestock. At worst, bites may cause brief pain, itching, and inflammation.
No long-lasting health effects or fatalities have been documented in pets. Some possible signs of a bite in pets include:
– Excessive licking or scratching at bite site
– Visible swelling/redness
– Pain evidenced by whimpering or guarding
– Mild lethargy or nausea
These symptoms are usually self-limiting. But if severe or prolonged, veterinary attention may be warranted. Overall though, two striped ground spiders do not represent an aggression or toxicity threat to domestic animals beyond temporary discomfort.
Range and Habitat
The two striped ground spider has a distribution across the eastern half of the United States and southeastern Canada. Their range includes:
– Eastern US from New England to Florida west to Minnesota, Iowa, Arkansas
– Southern Ontario and Quebec in Canada
Within this range, they can be found in a diverse array of habitats:
– Forests – Often hide under logs, rocks, leaf litter
– Rural settings – Common in barns, sheds, woodpiles
– Urban environments – Occur in man-made structures and landscaping
– Coastal areas – Live in sand dunes and beach debris
Two striped ground spiders are highly adaptable and occupy disturbed environments readily. They prefer cool, moist microhabitats on land and are not aquatic.
Biology and Identification
Here are some key facts about two striped ground spider biology and identification:
| Scientific Name | Acantholycosa lignaria |
| Other Common Names | Woodlouse spider |
| Body Length | 6 to 20 mm |
| Coloration | Yellowish with dark stripe on each side |
| Body Shape | Oval, robust |
| Legs | Short, stout relative to body |
| Eyes | Six small eyes in two rows |
| Behavior | Nocturnal hunter, lives on ground |
| Prey | Insects, invertebrates, spiders |
| Reproduction | Males court females with vibrations |
| Egg Sacs | Laid under rocks, logs |
| Life Cycle | Annual, die by winter |
The stout body shape, ground-dwelling habits, and distinctive markings help distinguish them from other spiders. They can readily be identified by the two bold longitudinal stripes when viewed up close.
Bite Treatment
As two striped ground spider bites are generally harmless, no specific antivenom exists. Treatment is focused on symptom relief and monitoring for infection:
– Clean and dress bite site
– Apply cold compress to relieve pain/swelling
– Take OTC pain medication (acetaminophen, ibuprofen)
– Topical antihistamines and hydrocortisone for itching
– Observe for signs of infection – seek care if worrisome
– Seek medical attention if severe systemic symptoms develop
With only mild symptoms in most cases, two striped ground spider bites usually resolve on their own within a few days with just basic first aid measures. Only persistent or worsening skin lesions or systemic effects warrant medical evaluation. But hospitalization and antivenom are never necessary.
Conclusion
In summary, the two striped ground spider is a relatively harmless species despite its ability to bite defensively. While their venom can subdue small prey, it poses little toxicity threat to humans. Bites virtually never cause significant reactions beyond some minor pain, redness, and itching. With proper first aid and wound care, symptoms can be treated at home. Two striped ground spiders do not represent a medically dangerous spider species. However, those with sensitivity to venom should still use caution and watch for any severe reactions following a bite. With proper identification and an understanding of their low toxicity, two striped ground spiders present negligible risk to humans working or living in areas where they are found.
