These bark beetles live in and feed on the
phloem in the inner layer of
bark on trees. They usually inhabit dead, dying, and stressed trees, including fallen trees, cut logs, and
slash. They can be found in trees that are already damaged by
drought,
lightning, human activity, or pest infestation. Typically, a male establishes a nuptial chamber in a log and produces an
aggregation pheromone that attracts both males and females. The males dig additional chambers and each female joins one of the males, digging an extension onto his nuptial chamber where she deposits her eggs. A male may have a harem of up to eight females. Exceptions are
I. latidens and
I. avulsus, which are
monogamous in nature. The beetles are called engravers because of the long, grooved galleries they excavate in the
sapwood. As the female digs her branch off of the male's nuptial chamber, she deposits eggs in individual niches along the walls. When the larva emerges, it digs a tunnel off of its niche. The multibranched
engraved galleries that result are often Y-, H-, or I-shaped.
Ips galleries are clear and open, unlike those of some other bark beetles, which are filled with wood dust and
frass. The beetles grow and develop more quickly during the warmer seasons. In the summer,
I. grandicollis and
I. calligraphus can complete an entire life cycle in 25 days, and there can be up to eight generations per year.
I. avulsus can complete a life cycle in just 18 days and have 10 generations per year. After
pupation, the new adult beetle
disperses from its birthplace and can fly several miles to locate an appropriate host tree in which to breed. Some species
overwinter in aggregations inside the galleries, while others seek shelter in the outer bark layers or the
leaf litter. ==Effects on trees==