Desert Insects and Spiders

The sight of a tarantula is likely to evoke strong reaction in people, either because they are fascinated by these large spiders or because they are extremely fearful. 

Here is Arizona, it is not uncommon to spot large tarantulas wandering around at certain times of the year, particularly in September and October.

Typically the wanderers are male tarantulas out looking for females. The females mostly stay in their silk-lined burrows and are rarely seen. How can you tell it is a male? The males have thinner bodies and have black on their legs and abdomen. The females have thicker bodies and are mostly light brown.

One of the first questions most people have is whether tarantulas have a poisonous bite. Generally tarantulas are not aggressive, but will bite if unduly alarmed. Like other spiders, tarantulas have a venom that is harmful to the insects and other small animals that they feed on. It isn’t thought to be unduly harmful to humans, but any time an animal bites and injects proteins into a wound, there is a chance for the susceptible recipient to have an allergic reaction to those proteins.

Surprisingly, tarantulas’ chief defense isn’t their bite at all, but something that looks harmless:  their bristles! The bristles on the back of their abdomen are urticating (cause an itching, stinging sensation). When stressed, tarantulas kick the bristles into the air. The bristles have barbed ends that can irritate the eyes and nose, and if they get on the skin they can cause an itchy rash.

Tarantulas may also use special bristles on their pedipalps and/or legs to stridulate. Stridulate means they rub the bristles together to make a buzzing or hissing noise. Some types of tarantula do this when they are scared or startled. In this video a pet owner provokes his pet to get it to stridulate. He writes that the tongs he used only startled the animal and it was not harmed. 

© Roberta Gibson 2015