Any organism that lives in one place for a long enough time is going to have to deal with pests. For mammals, this often means fleas and ticks. Nests, dens, and other roosting spots tend to accumulate high numbers of these blood suckers the longer they are in use. As such, anything that can cut down on pest loads in and around the home has the potential to confer great advantages. Evidence from California suggests that wood rats may be using the leaves of a shrub to do just that.

Dusky-footed wood rats (A.K.A. packrats) build giant nests out of twigs and other plant debris. These nests serve to protect packrats from both the elements and hungry predators. Packrat nests can last for quite a long time and reach monumental proportions considering the size of the rat itself. Because they use these stick nests for long periods of time, it should come as no surprise that they can build up quite a pest load. Fleas are especially problematic for these rodents.