It is a predatory beetle that eats other invertebrates, which makes it a valuable pest control agent in agricultural settings.

[2] The larvae of this species of beetle have been observed exhibiting cannibalistic behaviorisms in high population densities.

In addition to walking, flight capabilities resulting from wing dimorphism contribute to the beetle's ability to traverse wide ranges.

In North America, the beetle is found on both the west and east coasts of the continent, but has been documented steadily moving into the center of the US.

The beetle can inhabit habitats including forests, meadows, urban areas, and arable land.

The main conditions that would have to be met for the beetle to colonize and thrive in a habitat are temperatures suitable to larvae development and availability of food resources.

A study in 2021 modeled the expected distribution of P. melanarius based using several RCP scenarios.The study confirms that the most important factors influencing changes in the beetle's distribution are mean temperature during the warmest and coldest times of the year, as well as precipitation levels during the driest periods of the year.

To maximize probability of larvae surviving and having access to resources with needing to travel, female beetles select shaded and wet environments to lay their eggs.

[2] P. melanarius, as larvae and adults, is an omnivorous predatory beetle that feeds on insects, invertebrates, and plants.

[9] This behavior is characteristic of Lévy-flight patterns, which are optimal for widely dispersed prey that may not always be fully consumed at one time, such as slugs.

The beetles have many predators, primarily birds, but also "mice, bats, hedgehogs, shrews, frogs, toads, and occasionally moles.

Tillage in the spring can disturb larvae and pupae in the soil, resulting in a decrease in the number of fully developed adults able to breed that emerge later in the fall.

Since beetles that are starved spend more time foraging for food, P. melanarius has increased activity in insecticide treated fields.

[2] An important method to decrease the negative impacts of harmful agricultural practices is to utilize cover crops and intercropping.

In fields that used these agricultural control methods, which often require less tillage and chemical use, there was a greater abundance and activity levels of P.

[2][3] Moreover, these habitats are ideal for female P. melanarius, which prefer to oviposit in "structurally complex environments" to provide more protection their eggs and larvae.

[3] Several studies have determined that P. melanarius have had more rapid and expansive distribution in regions of Canada compared to other invasive carabid species.