. Their
mandibles, when closed, cover the
labrum. As a subfamily, they nest in a wide range of host plants, but any one species may show definite adaptations or preferences for particular groups of plants. Carpenter bees are traditionally considered solitary bees, though some species have simple social nests in which mothers and daughters may cohabitate. Examples of this type of social nesting can be seen in the species
Xylocopa sulcatipes and
Xylocopa nasalis. When females cohabit, a division of labor between them occurs sometimes. In this type of nesting, multiple females either share in the foraging and nest laying, or one female does all the foraging and nest laying, while the other females guard. Carpenter bees can be timber pests, and cause substantial damage to wood if infestations go undetected for several years. Two very different
mating systems appear to be common in carpenter bees, and often this can be determined simply by examining specimens of the males of any given species. Species in which the males have large eyes are characterized by a mating system where the males either search for females by patrolling, or by hovering and waiting for passing females, which they then pursue. In the other mating system, the males often have very small heads, but a large, hypertrophied
glandular reservoir in the
mesosoma releases
pheromones into the airstream behind the male while it flies or hovers. The pheromone advertises the presence of the male to females. Male bees are often seen hovering near nests and will approach nearby animals. However, males are harmless, since they do not have a stinger. Female carpenter bees are capable of stinging, but they are docile and rarely sting unless caught in the hand or otherwise directly provoked. However, carpenter bee nests are attractive to
woodpeckers, which may do further damage by drilling into the wood to feed on the bees or larvae. '', the blue carpenter bee, engaged in
nectar robbing Carpenter bees have short mouthparts and are important
pollinators on some open-faced or shallow flowers; for some they even are obligate pollinators, for example the maypop (
Passiflora incarnata) and
Orphium, which are not pollinated by any other insects. They also are important pollinators of flowers with various forms of lids, such as
Salvia species and some members of the
Fabaceae. However many carpenter bees "
rob"
nectar by slitting the sides of flowers with deep
corollae.
Xylocopa virginica is one example of a species with such
nectar robbing behavior. With their short labia the bees cannot reach the nectar without piercing the long-tubed flowers; they miss contact with the anthers and perform no pollination. In some plants, this reduces fruit and seed production, while others have developed defense mechanisms against nectar robbing. When foraging for pollen from some species with tubular flowers however, the same species of carpenter bees still achieve pollination, if the anthers and stigmata are exposed together. Many
Old World carpenter bees have a special pouch-like structure on the inside of their first
metasomal
tergite called the
acarinarium where certain
mites (
Dinogamasus species) reside as
commensals or symbionts. The exact nature of the relationship is not fully understood, though in other bees that carry mites, they are beneficial, feeding either on
fungi in the nest, or on other harmful mites. == Predators ==