If you're like many central Indiana homeowners you may have encountered massive hornet-like insect flying around your yard. As frightening as they appear, fear not, they are harmless. These are are in fact, wasps and they are routinely called Cicada Killers. In fact, they are usually only aggressive toward their main source of food, the Cicada. Unfortunately, because of their size and the fact that they often live in lawns and landscapes close to where people live, cicada killers evoke a great deal of anxiety. These wasps are huge and look very much like oversized yellow jackets but they have some very important differences. First, cicada killers are not social wasps that build colonies and protect their queens. Because they have no colony or queen to protect, they are not aggressive and have no reason to sting people. Cicada killers are one of the largest wasps that burrow into the ground in this area. At first glance, they are a very large, ominous looking wasp resembling a hornet or yellow jacket and evoke a good deal of fear. However, most of the wasps encountered are males, patrolling the nesting area. They may fly about, dive bomb, or even hover in front of, but they cannot sting people. They do not possess a stinger. Females do not defend their burrows, and will sting only if handled. Female cicada killers dig burrows in well drained, light textured soil, typically in an area with full sunlight. The 1½ inch diameter opening leads into an oblique tunnel that runs for 12-18 inches and reaches a depth of 6-10 inches. The female completes and stocks up to four cells, each containing from one to three paralyzed cicadas on which eggs are laid. When eggs hatch the larvae bore into and feed on the cicada. Secondary tunnels are often built off the primary tunnel; thus each female may rear up to 16 larvae in a burrow. Cicada killer wasps are beneficial and do not pose danger in most cases. When possible they should be left alone.