A black widow spider is black with a red mark on it's abdomen; this might or might not be what you meant. The black widow sometimes has a red mark on her back, as well. The red backed spider of Australia, a relative of the black widow, has an orange red mark on the back.
A spider with a red stripe on its back is the redback spider, which is found in Australia. They have toxic venom that can cause a human to become very sick.
A red diamond back of course
A black widow
The spider that is black with a white crescent on its back is the Brown House Spider. This spider is often confused with the red-back spider.
A black spider that has a red stripe on the back is possibly a red spotted ant mimic spider. They walk on six legs instead of eight and can be found in Arizona.
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Could be a Black and Yellow garden spider, common the US west coast.
# i don,t know i just fond a red spider with a black butt and black tips on feet and black fangs let me know if you find out
The spider you are describing is mainly found in Australia. Its called a red back. Very Very Poisonous.
It may be a Black Widow spider. They are very poisonous and it is probably best not to approach it if you are unsure of the species. Black spiders have a distinctive red "hourglass" shape on its back.
A black spider with a red mark and green fangs might be a black widow spider. This spider is very venomous and its bite can kill a human if treatment is not received soon after a bite.
a wolf spider. they hurt but are not deadly to humans
red back spider
A RED BACK!!! bY THE WAY I WOULDN'T TOUCH IT!! THEY ARE REALLY DEADLY, ESPECIALLY THE BABY ONES!!! ^ i wouldn't pay attention to that If the red is on the belly then worry more, it the red is on the back its not a black widow, ive seen a bunch of spiders with a black body and white stripe, they are jumping spiders, the red button i don't know much about.
black widow