Which two spiders are identified as poisonous in Iowa?

The identification of the brown recluse and black widow spiders as poisonous in Iowa is accurate due to their well-documented venom and potential health risks to humans.

The brown recluse spider, known for its distinctive violin-shaped marking on its back, can deliver a venomous bite that may lead to severe tissue damage and systemic reactions in some individuals. These bites can cause serious medical issues, including necrosis, particularly in sensitive populations.

The black widow spider is recognized by its glossy black body and the characteristic red hourglass marking on the abdomen. Its venom is neurotoxic and can cause severe pain, muscle cramps, and other significant systemic symptoms. While fatalities from black widow bites are rare, they can occur, especially in children and the elderly.

In contrast, the other choices each refer to spiders that are generally considered harmless to humans. The wolf spider and orb-weaver, for example, do not possess venom that poses a serious threat to people. Similarly, tarantulas are large but mostly non-aggressive and their venom is not typically harmful to humans, and both the garden spider and jumping spider are also regarded as non-threatening.