Unknowns – moth and bug.
What are these? Thank you very much for your consideration. Jon……
This is a very large moth, approximately 4 to 4 1/2 inches in length and was found on the exterior wall of our home one evening when the outside lights were left on. The time of year was August, during our monsoon season. We are at the 4,700 ft. elevation in the oak- grassland habitat of the Madrean Archipelago (Sky Island Country) of southeastern Arizona, 15 miles north of the Mexican border. This bug is found beneath rocks, lumber, buckets – wherever there is a covered and moist area. Unfortunately, they have found a way into our home, and they are active mainly at night. They can be flushed from the concrete patio edge at the patio/lawn interface by hosing down the concrete and they come swarming out of the wet ground and grass. They are constantly in motion and it is a rare moment when they are stationary. This one was feeding on the dead carcass of its own species. Occasionally, they will fly short distances. When they think you are too close, they will release a visible vapor puff from the distal tip of their abdomen with an audible "pop." Harmful? Dangerous?

Citheronia splendens Bombardier Beetle

Hi Jon,
We are thrilled to receive both of your photos. The moth is Citheronia splendens, a species found in upper elevations in Arizona and Mexico. The beetle is a Bombardier Beetle in the genus Brachius, and your description of its defense is very accurate. They are predators, so beneficial, and harmless to you. According to BugGuide: “Adults have impressive chemical defenses, ejecting toxic, foul-smelling gases from their abdomen with a loud popping sound. The explosive brew is composed of hydrogen peroxide, hydroquinone, and catalytic enzymes. ”

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