Chapulines are grasshoppers. They're prepared by frying on a comal - a metal grill hot plate - with garlic, lime juice and salt, mixed with a dried extract of special gusanos, the worm found in maguey. Sold all over the city by street vendors, market stalls and in restaurants, the protein-rich, salty critters are eaten as a snack, in tacos, and even as a pizza topping