Non-toxic huntsman spiders (like the one pictured above)are often mistaken for poisonous wandering spiders.
ISTOCKPHOTO/DIGITAL69

Last week, a store manager at a Whole Foods in Tulsa, Okla., was surprised—to say the least—to find a large brown spider lurking in a bunch of bananas. The spider was initially identified as a Brazilian wandering spider,  a menacing-looking creature with furry fangs and legs as long as five inches (12.5 centimeters) that is considered to be one of the world's most venomous spiders, and one of the few that can kill humans. (Luckily, an anti-venom to the Brazilian’s bite was developed in 1996.)

According to the Tulsa World, two local entomologists in the end determined that the invader was more likely a huntsman spider, which is large and brownish in color like the Brazilian wandering, but is nontoxic to humans.

Each year, there are several news reports of wandering and huntsman spiders, the main "banana spiders," showing up in grocery store bananas as well as poisonous black widows, which find their way into bunches of grapes on store shelves. Both fruits are generally sprayed with pesticides to prevent insect infestation and usually washed before shipment. Still, even with these precautions and visual inspections, some insects manage to survive.

What draws spiders to bananas and grapes—and what should consumers and produce workers who find the potentially deadly critters in their fruit do?

To find out, we spoke with Linda Rayor, a spider expert and senior research associate  in Cornell University's entomology department.

[An edited transcript of the interview follows.]


How common is it to find a spider in grocery store fruit—and are spiders more common in grapes and bananas from certain regions?
For the bananas, you have a reasonable chance of getting them in ones imported from anywhere in Central or South America, the main sources of the fruit. I have no idea of the actual risk, but there are different types of wandering and huntsman spiders throughout Latin America. You pretty much have a chance of getting black widows—which are found all over the world—in grapes anywhere they grow.

Is there something else about grapes that black widows find especially appealing?
Spiders are going to be found anywhere that there are insects for them to eat—and there are plenty of insects on grapes. They're very common in vineyards around the world. Grape arbors (the supports between grapevines) provide really great support systems for spider webs—they're perfect for cobweb-building spiders like the black widow—and the grapes make great hiding places. (Black widow bites can be toxic to humans, but they’re not nearly as dangerous as those from the most poisonous wandering spiders. They can cause intense pain and shortness of breath, but are rarely lethal in healthy adults.)

How about bananas?
Banana trees have these tightly coiled leaves coming up, and then the banana flowers lean down over that. Well, these banana leaves turn out to be just dandy places for these spiders to live, especially ones that hang out on the leaves. The leaves have this kind of hollow center, so a lot of the spiders hang out in the central, deep-covered hole during the day and then come out at night to hunt on the outside of the leaf. Neither one of them are web-building spiders, and so they just kind of hang out on the leaves at night and nab things that wander or fly by.