Big Bend Expeditions

Coelho and biology major Elizabeth Maty took a trip to Big Bend National Park in Texas to conduct research on wasps in June 2005. The work was collaboration between Coelho and other scientists from Lafayette College (Pennsylvania) and Northern Kentucky University. The group assembled at Big Bend because it is one of few places where three different species of cicada killers occur together. Cicada killers are large wasps that hunt cicadas to feed to their offspring. The research team documented the seldom-seen behavior of cicada killers feeding on sap oozing from trees, and the defensive behaviors the wasps used to push away competitors. The western cicada killer was found to maintain a fairly constant body temperature throughout the day. Coelho and Maty performed experiments that showed that this wasp has a mechanism to unload excess heat. It sends hot blood to its abdomen, which readily dissipates the heat because it is not insulated. This method has not been demonstrated in any other wasp, including the eastern cicada killer.

Big Bend, the least-visited National Park in the country, is situated along the Rio Grande River in southwest Texas. Conditions were difficult, as temperatures reached above 100 degrees every day The group saw a great deal of wildlife, including roadrunners, whiptail lizards, scaled quail, jackrabbits, javelinas, golden-fronted woodpeckers, vermilion flycatchers, and a rattlesnake.



left to right: Patty Holliday, Meghan Swigart, Angela Mendell, Jon Hastings, Joe Coelho, Elizabeth Maty

In May 2006 many members of the team returned to Big Bend. More research was done, primarily on another digger wasp, the much smaller Bembix troglodytes.