Gecko Collection: A Vital Resource

Geckos are amazing. Depending on the species — there are 1,500 species — they can defy gravity, glide through the air and even run on water (sort of). Geckos live in warm climates on all the continents except Antarctica. In the U.S., their native range is from southern California to South Texas.

So what are they doing in Stacey Wright’s Northeast Philadelphia living room?

“I think it came in when I moved a plant inside from the porch. The cat saw it before I did,” said Wright, who happens to be an Academy Visitor Services coordinator. “I had to fight the cat to get it. I didn’t want the cat to eat it in case it’s poisonous.”

gecko on rug
The Mediterranean house gecko in Stacey Wright’s living room. Photo by Stacey Wright

Being a typical Academy employee who cares deeply about nature and the environment, Wright wrestled the few-inches-long gecko from her cat, secured it in a plastic cup for her SEPTA commute to work, and handed it over to Herpetology Collection Manager Ned Gilmore to be identified, catalogued and subsumed into the collection.

Turns out the critter is an insect-eating Mediterranean house gecko, Hemidactylus turcicus, an invasive species spotted with increasing frequency hanging out on the exterior of houses in Philadelphia’s Fox Chase, Northern Liberties and South Philly neighborhoods. Several have made their way into Wright’s living room.

All this has made the Academy’s gecko specimens and research data a hot commodity these days, as researchers from the community science project GeckoWatch are using the information to track the distribution of geckos where they don’t usually occur in nature. We asked for an explanation from Gilmore and gecko expert Aaron Bauer, PhD, professor of biology at Villanova University.

Holy Gecko! Are we being invaded by Mediterranean house geckos?

Gilmore: I wouldn’t say invaded, but they seem to be all over the place. There was a population in Baltimore for a while, and now they are spreading in the Philadelphia area.

Should we be worried?

Gilmore: They eat roaches, spiders and other insects, which is not necessarily a good thing but maybe it is if they are in your house.

Why did you choose to study the Academy’s collection of geckos?

Bauer: Pennsylvania and New Jersey are a “new frontier” in the expansion of geckos, and the Academy is the one collection that has voucher specimens that confirm their occurrence in the region.

How is the Academy’s collection helpful to your research?

Bauer: The Academy’s collection allows us to confirm the specific identity of the geckos, and it helps us date the arrival and spread of the geckos in the region. In addition to Hemidactylus turcicus several other gecko species have introduced populations in the U.S.

Mediterranean house gecko. Photo by Robert E. Espinoza/California State University, Northridge

How did the Mediterranean house gecko come to the Philly area in the first place?

Bauer: Geckos (or perhaps their eggs) were likely accidentally transported with goods being shipped from some place where the geckos were already established.

Stacey Wright’s gecko is now a specimen in the Academy’s Herpetology Collection where it is available to scientists doing future research. Photo by Ned Gilmore/ANS

Does climate change have anything to do with the spread of this gecko species to Philly?

Bauer: Philly’s winters are too cold to allow the geckos to live outside year-round.  So, although climate change may have allowed the gecko to expand northward in the southern U.S., its arrival in Philadelphia is more a matter of chance. Nonetheless, warming temperatures may mean that their chances of becoming established are better and that the chance of more introductions may increase.

Trying to sneak in a Philly house. Photo by Adam Knapp

What are you finding so far in your Philly gecko project?

Bauer: Our data from Philly complement work all over the country that shows us that this gecko is amazingly adaptable. In their natural habitat in the Mediterranean, they occur in very restricted habitats. Once they got to America, however, they found a way to survive in the deserts of the southwest, in subtropical Florida, in continental climates in the southern Midwest, and now in the urban Northeast. Philly is especially interesting because the geckos must overwinter in protected habitats inside houses or other buildings. Thus, we would predict that their ability to spread would be limited in comparison to areas where they can move freely throughout the year.

Anything else you’d like to add?

Bauer: Modern transportation systems for goods, both nationally and globally, coupled in some places, with climate change, make the spread of introduced species ever more common. Although we now know that geckos are here, it will be important to keep tracking them to understand how and why they move through the area or remain localized. People can help by taking cell phone photos of geckos with date and geographic coordinates and providing this to GeckoWatch.

By Carolyn Belardo, Aaron Bauer and Ned Gilmore

We need your support now more than ever. If you believe that science matters, please consider a donation to support the Academy’s efforts to ensure a healthy, sustainable and equitable planet.

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In the Academy’s “Spotlight on the Collections” series, we tell stories about specimens chosen by our scientists and also how researchers and others around the world depend on our collections for issues involving climate change, water quality, evolution, and biodiversity and extinction.

To read the first installment in the Spotlight on the Collections series, visit “Protecting America’s Food Supply.”


    1. My 10yr. Old pointed them out to me while we were at the playground in Manayunk, she told me the were an invasive species & needed to be reported. I looked them up & sure enough!

  1. Hi ya, I’m so scared of gecko mostly there saliva as they are warning us that there saliva is dangerous and can kill humans in an hours, so how true is that? You should try and get them from us here as they are huge many here.

    1. Yes unfortunately their saliva secretions if made available to your skin ,especially your neck and eyes,has in its makeup a softening agent that can within an hour or less loosen the skin and allow the release of much of the vascular system in that immediate area making it ready to be consumed! No just kidding! They are harmless and usually make good house friends! There are many people that consider them as very good luck and are there by choice in happy environments! Mark

  2. I collected 4 adults and 4 baby’s at my work area in conchehocken this week bought them home and will release them in my yard hopefully they will stay and breed in the future

  3. I live in Arkansas, and I have a new pet gecko that I caught in my kitchen yesterday. It’s a very young Mediterranean geck, but I don’t know exactly how young. It’s definitely not large enough to eat even the smallest crickets available from my local pet store, though. It seems surprisingly calm and intelligent for a lizard and will climb onto my hand and look directly at me.

    1. Too small? Please forward any info you receive to me. I have a small plant growing operation and tons of bird seed in my home in Ohio do not use chemicals. Used to use house geckos in my aquarium shop for insects but everything I find on geckos wants to kill them not utilizing them.

  4. Im 56 years old and live in south Texas. All my life I had a phobia of these things that were ALL over my childhood home..The porch, in my bath water, in thekitchen sink, in the washer… they were just every where and it was my nightmare. I can’t even begin to tell you the legnths I went to try to enter my house with geckos all standing guard around the my front door.. But the geckos were a solid tanish pink. As time passed I started noticing more and more spotted geckos and now mostly that’s what I see when I do see geckos. In the last few years I noticed that I don’t see many geckos any more but now notice a new lizard which I have googled ( brown anole) another invasive species. I’m wondering if these new critters taking over my patio have driven out the geckos?

  5. I live in Central Alabama, near Montgomery. In the last 5 years Mediterranean House Geckos have taken roost on my home’s exterior. It started with one or two, now there are 8-12. I have noticed that they eat a lot of insects and spiders. I’m sorry about the spiders, but between the geckos and the Phoebe’s (a bird), I did not have one mosquito bite this past summer. I spend quite a lot of time outside in my yard.

    I also removed a baby MH Gecko from my house a few weeks ago. Upon handling it, it appeared to be very calm, did not attempt to bite, and when I took it to the yard to release it, it stayed perched for several minutes on my hand before I finally placed it in my garden. After what I’ve experienced with this spieces, I’m all for them being right where they are. I like ’em!

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