The black gnats of California

Abstract does not appear. First page follows.

Two species of biting gnats of the family Ceratopogonidae (Diptera) occur in California. These are the valley black gnat, Leptoconops torrens’ Townsend, and the Bodega black gnat, Holoconops kerteszi Kieffer. They are both vicious biters and are frequently extremely annoying to man, livestock, and poultry. Although the adults are well known to all residents of the breeding areas, the immature stages—egg, larva, and pupa—have remained undiscovered up to the present time. This study was undertaken to discover these immature forms, to determine the breeding areas, and to provide as much biologic information as possible, as a basis for control.

Classification

There are four genera of closely related flies—Styloconops, Leptoconops, Holoconops, and Microconops—which differ markedly from all other genera of the family Ceratopogonidae. All authorities recognize this distinct group of genera as the Leptoconops group. (Enderlein (1936))4 established the subfamily Leptoconopinae to contain these genera. (Johannsen (1943)) distinguished the adults of the Leptoconops group as having 12 to 14 antennal segments and no radiomedial cross vein, whereas the other ceratopogonids have 15 antennal segments and possess the cross vein.

The larvae of Leptoconops and Holoconops, described later in this paper, show such marked differences from the usual ceratopogonid type of larva that the writers agree with Enderlein and accept the subfamily name Leptoconopinae for this group. The chief characters in which the larvae differ from the other ceratopogonids are: the presence of heavy mandibular rods which extend backward into the first or second thoracic segment; the presence of 21 or more body segments; and a great reduction in the pharyngeal skeleton, with the pharyngeal combs entirely absent.

Only two genera of the Leptoconopinae are known to occur in California. These are the genus Leptoconops Skuse, in which the females have 14 segments in the antennae; and the genus Holoconops Kieffer, in which the females have 13 segments in the antennae.