The Cicada insects are now emerging in some parts of the United States after 17 years of hibernation underground. They are harmless but very annoying with their courtship noise drowning out most everything else and also creeping out some people seeing millions of large beetle like insects crawling all over. The sound reminds me of ringing ears after a loud concert or a herd of overly hyper rattlesnakes rattling tails in unison.
Fun fact: Cicadas have green blood.
Photos on Flickr