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Pet Care. Pet Training. Pet Stories.
Pet Care. Pet Training. Pet Stories.

Which Household Insects and Spiders are Toxic to Pets?

05/20/2019 by JoAnna Pendergrass, DVM
May 20th, 2019 by JoAnna Pendergrass, DVM

The sight of an insect or spider in your home is probably an unpleasant surprise. Despite our best efforts at pest control, spiders and insects can still manage to find their way inside and set up shop. As a pet parent, you may wonder if the different types of household insects and spiders are toxic to your pet.

Generally, the insects and spiders you may see crawling around your home are not toxic to cats and dogs; they are more of a nuisance than anything else. That being said, there are a few little creatures that can be quite dangerous and toxic to our pets. This article will highlight these toxic pests and give you pointers for keeping insects and spiders out of your home.

Toxic Spiders

Fortunately, most household spiders are harmless and pose no toxic risk to your pet. A few, though, have toxic bites that require immediate and intensive veterinary treatment.

Black Widow

 Black Widow

Black widows are one of the most dangerous spiders in the United States. They are common in the southern and western US and like to live in quiet, undisturbed areas of a home. Female black widows are up to 1 inch long, look shiny, and have a characteristic red or orange hourglass on their backs; male black widows are smaller than the females and don’t have the hourglass.

A bite by a female black widow can cause the following symptoms in pets:

  • Drooling
  • Rigid muscles
  • Incoordination
  • Muscle tremors
  • Muscle cramping
  • Severe muscle pain
  • Vomiting and diarrhea

A female black widow’s venom can also cause dangerous blood pressure changes and paralysis of the breathing muscles. If your dog or cat is showing any of these symptoms listed above, take your pet to your veterinarian right away for treatment. Treatment is intensive and includes anti-venom, fluids, muscle relaxants, and pain medications.

Brown Recluse

The brown recluse spider is common in the Midwest and southern US. True to its name, this spider, which reaches about 1 centimeter long, likes to hide in dark, sheltered areas like dark closets, attics, and even shoes. The brown recluse, also known as the “violin” or “fiddleback” spider, has a characteristic violin-shaped mark on its back.

Brown recluse spider on white.

Brown Recluse

A brown recluse’s venom has substances that cause severe tissue damage. A dog or cat that is bitten by a brown recluse may have the following symptoms:


  • Vomiting
  • Chronic skin lesions
  • Bleeding or bruising


A brown recluse bite can also damage the liver and kidneys, which your veterinarian would be able to detect. Although there is no anti-venom for brown recluse bites, immediate veterinary treatment is required. This treatment includes supportive measures, like wound care.


hobo spider

Hobo Spider

Hobo spider

The hobo spider is primarily found in the Pacific Northwest. It is brownish-gray and reaches just under 1 inch in length. Like the brown recluse, the hobo spider likes to hide in dark places, such as shoes and under the covers. A hobo spider bite causes similar symptoms as those of a brown recluse bite.

Be mindful that a spider bite may not show up on your pet for several days. If your pet shows signs of a spider bite, keep your pet from licking the bite site, as this could worsen the symptoms.


Toxic Insects

Household insects are generally nontoxic to pets. For example, silverfish, those 6-legged creatures you may see crawling around in your bathtub, can be a huge nuisance to you but pose no danger to your pet. And while roaches aren’t toxic to dogs and cats, they can cause an upset stomach if eaten. Other harmless critters include moths, butterflies, ants, grasshoppers, and crickets.

The insects that are most toxic or harmful to pets include large centipedes (smaller ones will probably not have much venom), scorpions, wasps and bees, and this is most likely due to the pain these insects will inflict if they bite or sting your pet. They’re not usually found in a human home, but it’s been known to happen in certain geographic areas of the US. Your best defense against these creatures is to keep them out of your home. Below are some tips for doing so:

  • Seal cracks and holes on your home’s exterior.
  • Keep the vegetation outside of your home short.
  • Clean your home regularly to remove potential insect and spider hiding spots.
  • Keep your pet’s food tightly covered to prevent insects and spiders from crawling in.
  • Find an environmentally-friendly, nontoxic pest control alternative that can help keep insects out while not poisoning your pet too.

Overall, you can rest assured that your pet is safe from household insects and spiders. Do your best to keep the tiny invaders from setting up shop in your home.

Content provided by JoAnna Pendergrass, DVM. Dr. Pendergrass is owner and founder of JPen Communications, a medical communications company specializing in consumer education.

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