The Rove Beetles of Florida

Rove beetles are often abundant in habitats with large numbers of fly larvae – decaying fruit, carrion, and dung – where they are important predators of maggots. Because they are abundant in decaying fruit, they often are encountered during fruit fly surveys, but frequently are not recognized as beetles. This circular is intended as an introduction to this large, diverse, and important family of beetles. Because the family is so diverse in appearance and habits, the various subfamilies are characterized in more detail here than is usual in a publication of this kind.

Most rove beetles are slender and cylindrical with short elytra, the abdomen is flexible, and the antennae are simple. Adults are about 1 mm – 30 mm long (figs. 1 – 16). Adults of some other families also have short elytra, but in these (e.g., Meloe, family Meloidae, Conotelus, family Nitidulidae, Mayetia, family Pselaphidae, Rhipidius, family Rhipiphoridae) the abdomen has little flexibility and the antennae are strongly clubbed at the apex or otherwise modified. As defined here the family includes Micropeplinae and Scaphidiinae (usually treated as separate families). Earwigs (Order Dermaptera) are often confused with rove beetles, but have moveable forceps at the end of the abdomen and many-segmented antennae. Eggs of Staphylinidae typically are white, spherical, spheroidal, pyriform, or cylindriform. Larvae are elongate and campodeiform, their antennae with 3 or 4 articles, with a sensory appendage on the penultimate article and typically facing anteriorly, the abdominal apex with urogomphi typically present and articulated, each leg with a claw-like tarsungulus. Pupae of most Staphylinidae are white and exarate, but those of Staphylininae are obtect, pigmented and sclerotized (Frank 1991).

Adults of most species are nocturnal, or at least hide from light during daylight hours, and are confined to moist microhabitats; some exceptions are Stenus and Paederus which are active in daylight. Adults and larvae of most species are facultative predators, but some are specialist predators, some are mycophagous or saprophagous or even phytophagous, occasionally damaging flowers and turf. Larvae of Aleochara are parasitoids of dipterous pupae. Several species, especially of Aleocharinae, are obligate inquilines of nests of social insects (ants and termites). Larvae of Stenus, Astenus, and many species of Aleocharinae spin a cocoon before pupating. In general, adults are long-lived, with eggs, larvae and pupae developing in a few days to a few weeks. The few Florida species for which life cycle information is known, albeit unpublished, breed throughout the year, which is more typical of tropical than of temperate species.

Probably more than 462 species occur in Florida, though only 342 are now recorded (Frank 1986; Frank et al. 1989). Habits and appearance vary widely in this large family, so characteristics of the 16 subfamilies recorded from Florida are given below. Only for the small subfamilies Oxyporinae and Leptotyphlinae are there modem taxonomic works allowing identification of all known Florida adults to the species level. Only for a handful of Florida species (in the genera Apocellus, Belonuchus, Bledius, Cafius, Creophilus, Myrmecosaurus, Osorius, Oxyporus, Philonthus, Platydracus, Scaphisoma, and Thoracophorus) are there accounts of behavior of adults or descriptions of immature stages, due almost entirely to studies in other parts of their range. There are no accounts of population dynamics (bionomics).