Updated: Feb 27, 2020
During brief cold-snaps of 30-40 degrees, iguanas in Florida become so cold that they slow down or become entirely immobile and can fall from trees. Rest assured, they are not dead.
This provides an opportunity to remove the unwanted and invasive lizards from your property. However, if you plan to kill it, there are some rules. It is legal to euthanize them humanely. That means you must kill it in one fell swoop. If you harm the animal but don't kill it, it's a crime punishable by fines and possible jail time if it ends up to be gruesome.
Green iguanas are not native to Florida and although fascinatingly beautiful creatures, pose a threat to both infrastructure and some small native wildlife. The invasive species can cause damage to seawalls and sidewalks and leave rather foul piles of excrement on pool decks and backyards as they mark their territory.
Iguanas were first documented in the Miami area in the 1960's and now stretch along the Atlantic Coast in Broward, Martin, Miami-Dade, Monroe and Palm Beach Counties and along the Gulf Coast in Collier and Lee Counties. There have also been reports as far north as Alachua, Highlands, Hillsborough, Indian River and St. Lucie Counties.
Some things to consider:
You may not capture them and release them elsewhere. It is not recommended that you put them in the freezer, as scientists now know that it causes them pain as their brains crystallize.
Please call a professional.
More info here from Florida Fish & Wildlife Conservation Commission: http://bit.ly/FrozenIguanas