The spiders are native to the southeast and tropics, and are most prominent in late summer and early fall, the South Florida Sun-Sentinel said Saturday.
"They are worth their weight in gold in the number of insect pests they consume," said Clive Pinnock, manager of the Okeeheelee Nature Center. He said they feed on mosquitoes and other insects that plague summertime visitors.
Beyond consuming mosquitoes, the spiders have another benefit.
Glavis Edwards, spider expert at the Florida Department of Agriculture and Consumer Services, said the female banana spider is especially nutritious because of the egg mass in its belly.
Even considering their nutritional value, parks officials in Boca Raton and Fort Lauderdale try to relocate the spiders away from playground and picnic areas.
"I'm sure it would freak some people out, but they are typically harmless," Fort Lauderdale spokeswoman Shannon Vezina said.