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Being in the tropics, this is not at all uncommon. I remember the first time it happened to me ... at night, I'd stand ready to attack before opening the door, as they'd all scurry once the dome light came on. At first I tired to swap out the car, but a friend told me it's so common that she regularly bug bombs her car so that's what I eneded up doing. The rental car companies will reimburse you for the bug spray if you save and present them with your receipt (or, at least, that's been my experience).