Those neat, circular holes cut in leaves and flower petals might not be the work of caterpillars or other pedestrian pests, but the signature of a new leafcutter bee species discovered and exclusive to Texas–Megachile chomskyi.
The most prominent features of M. chomskyi and the other members of this species group in the subgenus Megachiloides are their elongate tongues and the unique mandible structure of the females.
Unlike the other representatives of the family that chew leaves or flower petals, many species of Megachile neatly cut circular pieces of leaves or petals for nest construction. Nests of Megachile are often constructed within hollow twigs or other similarly constricted natural cavities, but some species, including members of the subgenus Megachiloides, excavate burrows in the ground.
M. chomskyi, found only in Texas, is further distinguished by a specialized preference for the flowers of the widespread Onagraceae, or Evening-Primrose Family.
The subgenus Megachiloides remains one of the most problematic Megachile groups in North America, partially due to males and females of many species not being associated with each other.
As such, a large proportion of the species are described from one sex. Outdated identification keys and poorly-illustrated descriptions are are also contributing factors.
The genus Megachile is a cosmopolitan group of solitary bees, often called leafcutter bees. This is one of the largest genera of bees, with well over 1,500 species in over 50 subgenera.
The Texas M. chomskyi study was recently published in the peer review, open access journal ZooKeys.
Source: ZooKeys On-Line Journal