Dr. Wilson went down to Florida Bay, where there are thousands of little mangrove islands, got an exterminator from Miami and covered a number of islands different distances from the other islands so they could be fumigated in order to eliminate all of the creatures on this little island. He did this so he could then carefully record the rate at which insect species re-colonized the little island and their number. The result strikingly confirmed his hypothesis. That all ended up in a book by Robert MacArthur and him called The Theory of Island Biogeography.