As pupation progresses, their joints, faces, and tips of their legs change from tan to dark brown.

H. illatus is found in the Southwestern United States, primarily Arizona, Nevada, New Mexico, and California.

In captivity, they will eat freshly-killed mealworms, fruits, and vegetables.They are protein feeders and show preference for insects and eggs over other food.

In captivity, they can be kept together or with other insect species relatively safely, but they may eat wounded or vulnerable individuals like eggs, larvae, or pupae.

Adult beetles are capable of stridulation and produce a quiet but audible 'chirp' when agitated.