Spider Identification and Control

Why this matters

Spider service calls split into two distinct categories: nuisance-spider control (common household spiders generating customer anxiety) and medically-significant-spider control (brown recluse and black widow, which present real bite risk). The treatment approach differs substantially. Misidentifying a harmless cellar spider as a brown recluse leads to over-treatment; misidentifying an actual brown recluse as a harmless spider leads to safety incidents. This reference covers identification and the control approach for each category.

Medically significant spiders

Brown recluse (Loxosceles reclusa)

• Adult body: 1/4-1/2 inch (excluding legs)
• Color: light brown to yellowish brown
• Distinctive: dark "violin" marking on the cephalothorax (head/thorax), with the "neck" pointing toward the abdomen
• Eyes: 6 (most spiders have 8); arranged in three pairs
• Legs: long and thin; total leg span up to 1 inch
• Habitat: dry, undisturbed areas - basements, attics, closets, behind furniture, in stored boxes
• Behavior: nocturnal; rarely seen during daytime; not aggressive but bites defensively
• Range: south-central US (Missouri, Arkansas, Oklahoma, Tennessee, Kentucky, Texas) - does NOT range to the West Coast, Northeast, or Florida despite widespread customer claims
• Bite: necrotic in some cases; medical attention required

Black widow (Latrodectus species)

• Adult female body: 1/2 inch (excluding legs)
• Color: shiny black
• Distinctive: red hourglass marking on the underside of the abdomen
• Male: smaller, brown, less venomous; rarely bites
• Habitat: dark, undisturbed areas - wood piles, garages, outdoor sheds, retaining walls, under decks
• Behavior: nocturnal; bites defensively when disturbed
• Range: most of the continental US, more common in the south and west
• Bite: neurotoxic; medical attention required; rarely fatal in healthy adults

Common medically significant impersonators

Several spiders are mistaken for brown recluse:

• Wolf spiders: larger, hairier, no violin marking, 8 eyes
• Hobo spiders: similar size, found in Pacific Northwest, medically less concerning per current research
• Cellar spiders / daddy long-legs: very thin legs, small body; harmless

When a customer reports "I think I have a brown recluse," verify:

1. The geographic range - recluses are NOT typical west of mid-Texas or east of the Appalachians
2. The violin marking on the cephalothorax (NOT on the abdomen - common confusion)
3. 6 eyes in three pairs
4. The spider's appearance and size

In ~95% of non-range calls, the spider is misidentified.

Common nuisance spiders

Cellar spider (Pholcidae family)

• Very long, thin legs
• Small body
• Web in corners
• Eats other insects + spiders
• Harmless; often confused with brown recluse due to coloring

Wolf spider (Lycosidae family)

• Large body (1/2-2 inches)
• Hairy
• Brown / gray
• Active hunter (no web)
• Bites painful but not medically dangerous

Common house spider (Parasteatoda tepidariorum)

• Small (1/4 inch)
• Brown / gray
• Builds tangled webs in corners
• Harmless

Yellow sac spider (Cheiracanthium inclusum)

• Pale yellow
• 1/4 inch
• Active hunter; nighttime
• Bite: minor, healing in days

Hobo spider (Eratigena agrestis)

• Medium (1/3-1/2 inch)
• Brown
• Builds funnel webs near ground
• Range: Pacific Northwest
• Bite significance contested; current research downgraded from medically significant

Jumping spider (Salticidae family)

• Compact, hairy body
• 1/8-1/2 inch
• Vivid color patterns sometimes
• Active hunter; jumps to catch prey
• Generally harmless and beneficial

Treatment approach by category

Medically significant spider control

For confirmed brown recluse or black widow infestation:

Inspection:

1. Visual inspection of high-risk areas (basement, attic, undisturbed storage)
2. Sticky monitors deployed in suspect areas to capture and quantify population
3. Photo documentation of any spider captured for positive ID
4. Photograph the property for treatment planning

Treatment:

1. Vacuuming - physical removal of visible spiders, webs, eggs sacs. Vacuum bag goes outside immediately
2. Targeted pesticide application - residual insecticides labeled for spider control:

• Bifenthrin (general)
• Cyfluthrin (Tempo SC)
• Deltamethrin
• Lambda-cyhalothrin (Cyzmic CS)

1. Application points: cracks and crevices, baseboards, dark corners, undisturbed storage areas, garage perimeter, exterior foundation
2. Crack-and-crevice formulations for void application
3. Dust formulations (boric acid, diatomaceous earth) in long-term undisturbed areas

Customer education + sanitation:

1. Reduce clutter - boxes, undisturbed storage are recluse habitat
2. Sticky monitors stay in place for ongoing detection
3. Shake out clothing and shoes before wearing
4. Inspect bedding before getting in
5. Long-term follow-up inspection to verify population reduction

Brown recluse specifically: extremely difficult to eliminate; populations persist for years. Treatment goal is reduction to acceptable level rather than complete elimination. Set realistic expectations.

Nuisance spider control

For common spiders (cellar, common house, wolf, jumping):

Treatment:

1. Web removal - physical removal with extension pole, broom, or vacuum
2. Crack-and-crevice treatment of building perimeter
3. Exterior foundation treatment with residual labeled for spider use
4. Quarterly maintenance included in general residential pest control programs

Most nuisance spider issues resolve with the standard quarterly pest control service - no specialty visit needed. Web removal and exterior perimeter treatment handle the vast majority of cases.

Treatment products

Specific product selection based on the situation and the technician's license.

Web management

Web removal is the visible component of nuisance spider service:

1. Extension pole web brush
2. Sweep webs from corners, eaves, soffits
3. Vacuum webs in attics and garages
4. Pressure wash exterior surfaces (deck undersides, eaves)
5. Educate the customer on continued web management between visits

References

• USDA Cooperative Extension spider identification keys
• CDC Brown Recluse and Black Widow bite resources
• National Pest Management Association (NPMA) spider control technical bulletins
• EPA registered spider insecticide labels
• State pesticide applicator licensing requirements
• Manuall internal: Common Residential Pest ID, Quarterly Residential Pest Service SOP, Integrated Pest Management