Phanaeus vindex, also known as a rainbow scarab (like other members in its genus[1]), is a North American species of true dung beetle in the family Scarabaeidae.

[5] Because P. vindex is member of the Scarabaeinae sub-family, they are considered to be “true dung beetles” and feed exclusively on fecal excrement through all stages of their life cycle.

Research has shown that rainbow scarabs have certain preferences when selecting feces to feed on; they are most attracted to excrement that is considered “fragrant” or produced by organisms that have very diverse diets.

[5] When making the pear-shaped brood balls, P. vindex females perform what looks like a “butting” motion in order to push dung away from where it was originally placed.

This behavior attracts males, who will work with the female to make the dung into a ball and roll it into the chamber through the tunnel system they construct together.

Once all the eggs have been positioned in the chamber, the male and female pair construct a second tunnel which contains food for newly hatched beetles as well as those that remain below the soil in colder climates.

The larvae and both the molting processes happen within the brood ball; it is only when these beetles reach their adult stage that they emerge from the dung in which their parents housed them.

Both sexes of rainbow scarabs need to consume dung regularly in order to become sexually mature, but females especially need to have this particular diet so they can oviposit.

[10] Because P. vindex are able to inhabit such a wide range of habitats, research has been conducted to investigate whether their reproductive habits change according to environmental factors to maximize offspring growth and development, or whether they remain a consistent behavior across all members of the species.

However, reproductive behavior plasticity based on temperature differences can impact earlier life stage development, so this has been an area of focus.

Higher temperatures during development have shown to cause faster transitions between life cycle stages, smaller adult body sizes, and potentially, lower survival rates.

Additionally, although deeper nesting can protect offspring from high temperatures, it can cost parents time and energy, which can affect other fitness traits.

[7][11] However, studies have shown that up to an optimal temperature, cold-blooded organisms can become more productive, potentially allowing them to dig through and transport dung more efficiently.