The diel pattern of drifting adults, pupae, pupal exuviae, and larvae of Chironomidae in a stream was established. Emergence was trimodal for the common species (Cricotopus sp. and Psectrocladius sp.), and larval drift-rates increased almost two-fold in darkness. The concurrent diel consumption of Chironomidae by coho fry was examined. The fish appeared not to make use of the peak drift-rates of larvae. Closest temporal correspondence between drift and diet was shown by adults. Forage ratios demonstrated greater consumption of chironomids than would be expected from their proportions in the drift. The order of acceptance was pupae, adults, larvae, and exuviae. High degree of utilization of an item is attributed to flotation and visibility. The major determinants of how much food is taken from the stream are identified as: marginal residence of the fish, the occupation by the fish of slow-water feeding stations, and the visibility of food items.

The maxillae and prementa of Trissocladius grandis (Kieff.), Chironomus anthracinus Zett. and a tanytarsine species near Lauterbornia are figured and the fine details of their external morphology are discussed. The results of a review of larvae in other genera in the Chironominae and Orthocladiinae are briefly stated to illustrate the value of these morphological characters in comparisons among higher taxa within the Chironomidae.

Larval forms of Chironomidae were collected on the U.S. Virgin Islands and Anegada, British Virgin Islands. A total of 16 species were found and seven of these were reared to the adult. The species represented 3 subfamilies, 4 tribes, and 12 genera. Species of the genus Chironomus were the most widespread and abundant. In addition, 4 species of Ceratopogonidae and 1 of Chaoboridae were collected.

The emergence times of most European Clunio populations are correlated with certain conditions of low tide and time of day which occur together only every 15 days. This temporal programming of development is determined by the combination of two different endogenous rhythms: a semilunar rhythm which controls the beginning of pupation and a circadian rhythm which controls the diurnal emergence time. The paper summarizes the known characteristics of these two physiological clocks and their adaptation to different tidal and photoperiodic conditions in the field.

The occurrence and abundance of larvae of Chironomus tentans Fabricius in saline lakes in central British Columbia were studied with respect to: (1) physico-chemical properties of the lakes, (2) physical composition of the bottom muds, (3) food availability, and (4) co-occurrence with other species of chironomids. The study was done to determine the ranges of environmental conditions to which the larvae are adapted and to identify specific environmental factors which might be of particular significance to natural selection. Abundance was significantly correlated with the amount of food available; the numbers of individuals of other Chironomus present; the percentage of mud particles in the 0.59–0.83 mm range; pH; conductivity; and the concentrations of potassium, magnesium, chloride, sulfate, and dissolved oxygen. In general, occurrence was affected by the same factors which affect abundance. Additionally, larvae did not occur when hydrogen sulfide was greater than 0.3 p.p.m. The ecological data are particularly relevant since they provide a basis for studying the evolutionary significance of ecological adaptation in C. tentans.

Female midges were reared in isolation and allowed to produce unfertilized eggs. Some egg batches of Chironomus atrella, C. attenuatus, and C. stigmaterus showed evidence of parthenogenesis. In C. attenuatus 733 unhatched embryos and 191 hatched larvae were counted among approximately 9771 eggs produced by 12 females. In attempts to rear them, some of the parthenogenetic larvae attained the fourth instar.

It is proposed to consider the taxon Leptochironomus Pagast as a genus which includes: L. tener (Kieffer), L. aegyptius (Kieffer), L. stilifer (Freeman), and L. deribae (Freeman). L. paraderibae La ville and Tourenq is regarded as a synonym of L. deribae.The juvenile stages of L. stilifer are described. The opinion is expressed that the juvenile stages described as Chironominae genuinae No. 4 (Lipina 1927), Microchironomus conjugens Kieffer (Lenz 1926), and Microchironomus No. 1 (Zavrel 1931) belong to Leptochironomus.

Evidence is presented indicating that Harnischia Kieffer in the sense of Lenz is correct. Harnischia sensu Beck & Beck then becomes a synonym of Cryptocladopelma Lenz (which, however, is formally a nomen nudum). Synonyms of the genus Harnischia are given. Corrections and additions to the descriptions of Harnischia curtilamellata (Mall.) (syn. H. pseudosimplex Goetgh. syn. nov.) are given. The genus Harnischia is characterized. The phylogeny of the Harnischia complex is discussed.

Severely deformed chironomid larvae have been collected in Lake Erie and two lakes in the Okanagan valley of British Columbia. Deformed larvae had very aberrant mouthparts and the head capsules were usually heavily pigmented. In most cases both the head capsule and body wall were many times thicker than in normal specimens. These deformities are apparently caused by pollutants and it is speculated that agricultural and/or industrial chemicals may be responsible.

Populations of Chironomus tentans from Iowa and Wisconsin show consistent polymorphisms for inversion sequences of chromosome 1 which are associated with sex. Male larvae from Iowa populations are invariably heterozygous for a sequence of the left arm which is never present in females. In a Wisconsin population, however, females are consistently heterozygous for a dominant sex factor, female determiner (Fd), linked to but not inseparable from an inversion sequence of the right arm. Two primary loci for sex determination appear to have evolved different dominance relations in these races.

Some aspects of the characterization and delimitation of the chironomid genera are presented. The size and composition of the taxa and different types of splitting are discussed, with examples from Chironomus. Some opinions regarding the practical value of the category subgenus are weighed. Ideas about the relationship between phylogeny and classification are put forward, and some problems concerning the ecological characterization of genera are discussed.

Adult midges (Chironomidae: Diptera) were recorded at experimental ponds during all months. Data from 13 years were combined by months. Submerged traps yielded 50 species. Other methods of collecting obtained 15 additional species. Traps in 12 similar 0.1-ha ponds beside a permanent slow-flowing supply-canal yielded 45 species. Traps in a 1.95-ha pond that lacked such a canal yielded 15 species.

This preliminary report on a revision of the Tanypodinae of Africa south of the Sahara is based mainly on the collection of imagines in the British Museum (Natural History). It has been possible to re-examine most known species, in addition to studying new species, and to classify them according to the scheme proposed by E. J. Fittkau. Most species fit into his genera but a few new ones will have to be erected. The distribution of species is discussed.

On St. John, U.S. Virgin Islands, the leaf axils of two species of Bromeliaceae were sampled for dipterous larvae. One half of the collections were made from the axils of Tillandsia utriculata, restricted almost entirely to the dry, coastal portions of the island, and the other half from Aechmea lingulata, found in the moist mountainous regions. Three species of Chironomidae, representing three subfamilies, and five other families of nematocerous larvae were found. Though species of Diptera were found throughout the island, the Chironomidae and Ceratopogonidae were restricted to the dry areas, and the Culicidae were found predominantly in Aechmea lingulata, on Bordeaux Mountain.