When is a locust not a locust? When it’s a Magicicada! Periodical cicadas like the 17 and 13 year Magicicadas, are often called 17-year Locusts, probably because they emerge in massive numbers. Cicadas are not locusts, in fact, true locusts are grasshoppers.
Take a look that the illustration of a true locust below. You’ll notice the true locusts have long rear legs for hopping, long antennae, and relatively long bodies. True locusts chew the plants they consume, while Magicicadas suck fluids from trees.
Locust:

17-year cicada:

Thanks for showing the physical difference in the two – - we’ve been having discussions recently here in Indiana. Please show a link or sound differences in the two, as our locusts have that longer, drawn-out tone (up-down), and the long fade at the end. Very interesting.
-Caroline of Indiana
Comment by Caroline NativeFortwaynian — July 20, 2010 @ 12:19 pm
If you go to our Sounds page http://www.cicadamania.com/audio/ there’s cicada sounds to listen too, and then check out the sounds of insects page http://www.musicofnature.com/songsofinsects/iframes/specieslist.html for locust/grasshopper sounds.
Comment by Dan — July 20, 2010 @ 3:38 pm