Spiders in House
Estimates spiders inside a typical house by room count.
—
Spiders in your home
A 2016 NC State study (Bertone et al.) counted ~30-100 spiders in the average home, and most of them go unnoticed by the people living there. Brazil has roughly 3,500 species, but only three groups matter medically: the armadeira or banana spider (Phoneutria), the aranha-marrom or brown recluse (Loxosceles) and the viúva-negra (Latrodectus). Almost everything else is a harmless predator that feeds on cockroaches, mosquitoes and flies.
Numbers peak in autumn (Mar-May), the season when males roam looking for mates. Antivenoms come from Instituto Butantan (SP) and Vital Brazil (RJ); in 2024 the SUS distributed about 50.000 doses for arachnidism cases across the country.
Applications
Household pest management, public health work (Butantan, Vital Brazil), Anvisa control under RDC 52/2009, and the environmental Lei 9.605/1998, which protects predators.
FAQ
Are spiders dangerous? About 99% of the ones in homes are harmless. Try to identify before killing, since most are working in your favor.
What to do if bitten? If you can do it safely, photograph the spider. Wash the wound and head to a hospital that stocks antivenom.
How to reduce population? Cut off their food by dealing with other insects, seal up cracks, and clear out cluttered storage spots.
Related Tools
Isomalt Decor Percentage Amount Calculator
Computes the amount of isomalt in grams for sugar decoration from the desired volume and the percentage of added water.
Daily Magnesium Requirement
Calculate your daily magnesium requirement in mg according to sex and age. This mineral is essential for muscles, nerves and good sleep quality.
Great Wall Workers Calculator
Estimates how many workers were needed to build the Great Wall of China from total structure volume and average rate per worker year.
Home Purchase Down Payment
Computes 20% down payment savings plan and SAC monthly installment.
Gutters & Flashings Calculator
Calculate how many linear meters of gutters and flashings to buy for a roof from its perimeter. Size the right material for rainwater drainage.
NAD Supplementation in mg
Estimates daily NAD dose in milligrams.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.