Horned Passalus Beetle

Odontotaenius disjunctus is most commonly found in climates with higher humidity, mainly in the warmer parts of both hemispheres, and also widely distributed in temperate North American forests. O. disjunctus beetles are usually found under, or inside, old logs or stumps and are rarely observed outside of their wooden habitats.

Patent-leather beetles like to eat logs of certain trees, in which the wood is dead and decaying. They eat deciduous trees, such as oaks and elm. Wood inhabited by these beetles is usually well decomposed and falls apart readily. This unique food source prevents competition as these beetles have chosen a food source that is not highly sought after by other organisms due to the material being indigestible for most. Adults feed primarily on wood, while larvae stages eat materials composed of fungi, wood and parental secretions. Wood consumed by the beetles is digested with the help of a "fiber-associated microbiome" in the anterior hindgut that is composed of Lactococcus and Turicibacter. Interestingly, their ecology and approach to symbiotic digestion is similar to wood-feeding cockroaches of the subfamily Panesthiinae, that also appear to rely on a similar contribution from their hindgut microbiomes. Burrowing within rotting logs offers the triturated wood that is a staple in the diet of these beetles, this wood is consumed widely by the males and then further broken down through the digestive tract, and eventually expelled for the eventual re- consumption by all family members.

These beetles can be found in rotting logs, especially of oak and hickory. This specific locale offers unique benefits in regards to protection from predators and external abiotic factors such temperature and precipitation. There is a level of stability with the two factors mentioned, the water retention in the wood helps to keep temperatures stable while aiding in further decomposition of the log itself. The regulation of this environment allows for both day and night activity. Larvae can reach adulthood in as little as 3 months due to a rich food source, with the average lifespan of an adulthood being up to one year. Adults are only found outside of their log when they are searching for a new mate, or a new log in which to burrow. Daily movements tend to be limited to within their log, any movements outside of the log are not as predictable and occur much less frequently.