The cicada killer is one of the largest wasps in Indiana. The cicada killer is a solitary wasp that digs tunnels in the soil for rearing its larvae. Once the tunnel is dug to the appropriate depth, the cicada killer will fly off and make a circling flight around the nest area to memorize landmarks. It will continue to memorize landmarks during its hunt for a cicada.
A female cicada killer locates a cicada by its loud calling. The female will sting the cicada to paralyze it and fly with it back to the nest. The cicada killer will drag the cicada into the tunnel, lay an egg on it and seal the tunnel. By keeping the cicada alive, but in a paralyzed state, the cicada killer provides a large quantity of fresh food for its larva. Over the course of its development, the cicada killer larva will consume the entire cicada. The wasp must be large enough to carry an adult cicada back to its nest which is one reason for its large size.
When cicada killers are not digging tunnels and hunting cicadas, they visit flowers for pollen and nectar. A prime nectar spot for the wasp are wild carrot (Daucus carota) flowers. People who are afraid of bees and wasps are usually even more frightened of the cicada killer. Because of its large size, they assume that it must deliver a larger amount of a more painful venom. However, the cicada killer primarily uses its venom for paralyzing prey. It is not very aggressive in guarding its nest. When collecting nectar, it is possible to approach cicada killers very closely with little danger of being stung. Their large size and slow movements on flowers make them an easy insect to photograph close up.
Eastern Cicada Killer, Sphecius speciosus on Wild Carrot
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Its amazing how large they are! It took me by surprise when I saw them around campus at the beginning of the Fall 2009 semester. Aside from the size, they look potentially threatening. Although they aren’t typically aggressive, can they sting humans as well?
Justin Schmidt has written the book on insect venoms:
http://www.springerlink.com/content/p3l52507g7g20386/fulltext.html
Justin rates the pain level of the sting of another species of cicada killer, Sphecius grandis, at 1.5 on a 0-5 scale. The pain is described as sharp and immediate, but not burning, with a duration of 2-5 minutes. I have never been stung by one and don’t personally know anyone who has. Reports from people stung by Hymenoptera have a degree of uncertainty attached because most novices can not readily identify wasp species.
There are very few reports of people being stung by cicada killer wasps so the odds of being stung are fairly low. Their typical behavior is aggressive flight, which given their size is usually threatening enough without following through by stinging.
Most people are stung when they approach too near to the nest of a social wasp. From an evolutionary perspective, the selection for a venom that causes pain to vertebrates is much stronger for social wasps than for solitary wasps. Social wasps actively defend their nests and the resources they contain from vertebrate raiders. There is strong selection for the ability to deter vertebrate raiders by means of a painful sting. Solitary wasps, like the cicada killer, protect their food and young by concealment and entombing them underground. They do not patrol their nesting site. Selection is strong to maintain a warning coloration for defense against bird predation, but there is no selection for protecting the young by stinging.
Oh my…I remember seeing these things all over the golf course where I used to play. I got very scared due to their size, and they tend to hang around around the bunkers….So when my ball went into the bunker, me and my friends just left it there hahaha was too scared to go into the bunker to even grab the ball out. It seemed like these wasps make nests in soft soil (bunker sand) and they were large in number, I guess the place was a nice breeding spot. Or I’m mistaking them for another species of wasps. haha.
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