Spiders

Spiders (order Araneae) are predatory arachnids that, in the vast majority of cases, are beneficial: they naturally regulate populations of mosquitoes, flies, cockroaches and other insects in and around buildings. For this reason, Integrated Pest Management (IPM) does not aim to exterminate every spider, but rather to reduce the harborage where they thrive and to control only the species of medical importance. In Mexico, the two truly dangerous species for people are the black widow (Latrodectus mactans) and the brown recluse or fiddleback spider (Loxosceles spp.). An abundance of spiders indoors is often a sign that other pest populations they feed on are present.

Identification

Black widow (Latrodectus mactans): shiny black body with a red hourglass mark on the underside of the abdomen. Size 8 to 15 mm. Builds irregular, tangled webs close to the ground.

Brown recluse or fiddleback (Loxosceles spp.): uniform brown with a violin-shaped mark on the cephalothorax. Size 8 to 12 mm. It has six eyes arranged in three pairs, a feature that sets it apart from most spiders, which have eight.

Common spiders: various harmless household species that build webs in corners, basements and low-traffic areas. Their typical habitat is dark, quiet places: warehouses, garages, closets, behind furniture, woodpiles and unused shoes.

Signs of infestation

Identifying where and which kind of spider lives in a property is the first step toward responsible control. Watch for these signs:

• Build-up of webs in corners, window frames, beams and storage rooms.
• Whitish, silky egg sacs attached to webs and hidden surfaces.
• Sightings of spiders in low, poorly lit areas, especially when moving stored items.
• Presence of other insects (their food source), which points to an underlying pest problem.

Risks

The vast majority of spiders pose no danger and their bite is comparable to a mild sting. The risk is concentrated in the venomous species of medical importance. A black widow bite (latrodectism) causes intense pain, muscle spasms, sweating, nausea and, in severe untreated cases, potentially fatal complications. A brown recluse bite (loxoscelism) can cause tissue necrosis around the wound that sometimes requires prolonged care or reconstructive surgery. Both are more dangerous for children, the elderly and immunocompromised individuals. Beyond health, webs affect the image of shops, warehouses and customer-facing areas.

How Fucesa controls it

At Fucesa we take an honest Integrated Pest Management approach: because most spiders are allies, control does not mean spraying indiscriminately, but reducing harborage and directing action only at the species that pose a real risk:

• Inspection and identification: determining which species are present to decide whether intervention is needed or only harborage reduction.
• Harborage reduction and relocation: mechanical removal of webs and egg sacs, decluttering of storage areas and elimination of hiding spots; where possible, harmless spiders are relocated rather than killed.
• Controlling the food source: reducing the insect populations that attract spiders removes the root cause.
• Targeted treatment: only when species of medical importance (black widow or recluse) are confirmed are residual products applied to perimeters and activity areas by certified technicians.

Prevention

• Remove webs regularly and keep storage rooms, garages and warehouses tidy.
• Seal cracks and openings in doors, windows and foundations to limit access.
• Shake out clothing and shoes before wearing them and use gloves when moving stored items or firewood.
• Reduce excessive outdoor lighting, which attracts insects and, with them, spiders.

When to call a professional

It is wise to contact a professional when species of medical importance such as the black widow or the brown recluse are identified or suspected, when there are recurring infestations of common spiders linked to other pests, or in sensitive spaces such as schools, hospitals, hotels and warehouses. If someone is bitten by a venomous spider, seek medical attention immediately; if possible, capture or photograph the specimen for identification, and do not apply tourniquets or attempt to suck out the venom.

Fucesa has more than 40 years of experience in pest control. We operate with personnel certified under NOM-256-SSA1-2012 and registered with COFEPRIS, applying responsible Integrated Pest Management from our headquarters in Toluca and our base in Queretaro.