Going to the humid tropics may seem like visiting another world if you're from the USA. I've got a couple of stories about an invasive species to illustrate this, but first there's a climate review... which you can skip if you want. Just pick up again after the Koswiggle thing.
While every spot on the earth receives the same number of hours of light per year, the further north or south you travel from the equator...the more extreme the distribution of those hours becomes. So, in Alaska, you have some days with nearly 24 hours of light and others with nearly 24 hours of dark, and of course you have winter and summer. Most of the US has obvious seasons as a result of the unequal distribution of solar hours over the year.
The tropics, the area of the earth between the Tropic of Cancer and the Tropic of Capricorn, is notable for its more even distribution of solar hours over the year. Here in Panama, for example, it gets dark between 5:54 PM and 6:42 PM every day this year. Close to 12 hours of dark and 12 of light per day (actually between 11:36 and 12:38 in 2011), so there is no appreciable variation in temperature during the year. What is referred to here as winter (invierno) and summer (verano) is really wet season and dry season. Those two seasons don't correspond to our seasons of the same name and are instead due to the shifting of prevailing winds.
Don't worry if you don't remember the details, just remember that cold weather, Mother Nature's very own best pest control method, is not happening in the tropics. The exception occurs if you go way up in altitude (up in the mountains), which is similar to moving north or south, away from the equator.
World Map Showing the Tropics In Red
In the 1980s a "new" lizard, The Common House Gecko, set about living up to its name in Panama. It moved into houses big and small, city and country, and earned another name- lagartija limpia casa, house cleaning lizard. A native of southeast Asia and north Africa, it's gone cosmopolitan from the high rises of Singapore to Pacific Islands to Israel, Brazil, Central America and southern US. Have you seen them?
Here in Panama, its introduction was recent enough that people remember pre-gecko times. There used to be spiders and other creepy arthropods in abundance. Now there's a lot less of them, because.. there's little nocturnal house cleaners. If you're sitting around the cantina in the country having a few beers, you'll see several geckos on the wall and ceiling around the lights. When a moth or other insect shows up, attracted to the light, out darts the gecko, and opens a mouth that seems bigger than its head, and cleans house. It's kind of fun to watch, but some people think the gecko is a pest itself. My wife always says "ay no, they're transparent".
What I wrote up to this point was written while we were staying at my step-son's house in Panama City. There, the geckos were outside, though we could hear their call at night, which is amazingly loud for a creature between 3 and 6 inches long. It sounds like a demonic cackle laugh. Since then, we've moved to Chiriqui Province in the wild west, just short of the border with Costa Rica. It's the campo, the neighbors all have chickens, there's cattle down the street, and for some reason the water is shut off every night. And the damn geckos are in the house.
They are all over. They leave their distinctive little poops in the kitchen. They frolick on the walls in the bedroom. They cackle demonicly at night and wake me up. They lay little white eggs on the window sills. They get stuck on the glueboards (AKA sticky traps) we have out to kill insects. This morning I slid open a window and pinned one against the frame. He looked at me with his tiny black slitted eyes in his little orange translucent head. Good, I thought.
This invasive species is really getting on my nerves. They're not even that great at cleaning the house- we've got all sorts of insects also. It's the rainy season, and it never gets cold in the tropics, which after all is Mother Nature's best pest control method.
Update: The poll results and comments are clearly pro-gecko, and I'll just have to learn to co-exist. Can I mail any of you some geckos?
Second Update: I can feel the gecko love. I promise I won't kill them. My offer to mail them to anyone interested stands.