Observations were made during 1967 to 1969 at Ithaca, N.Y., supplemented by collections at New Cumberland and Carlisle, Pa., on arthropods associated with fungi occurring on alfalfa, Medicago saliva L. Five species of Coleoptera, two species of Diptera, one species each of Collembola and Psocoptera, and nine species of Acari were reared or collected consistently from fungus-covered alfalfa leaves, stems, and seed pods. Attraction to fungi on the plants, principally Alternaria sp., accounted for the presence on alfalfa of arthropod species that normally might be considered as accidentals or visitors. The mycetophagous species thus contributed to the richness of the alfalfa fauna. Immature stages of several species were collected only in late fall or on 3- or 4-year-old plants. The possible role of the fungus-feeding species in seasonal changes in the alfalfa fauna and changes in the fauna in successive years is discussed.

Oligotrophus papyriferae Gagné is univoltine in Michigan. Adults emerge in mid-May and the females deposit small egg clusters on the underside of the leaf near the petiole of paper birch (Betula papyrifera Marsh.). Larval eclosion occurs 1–2 weeks later; there are three instars. The larvae bore into and down the petiole and enter the stem or a bud attending the leaf base. Galls appear in early August. There are petiole-bud and petiole-stem galls, depending on which tissues are infested. Third-instar larvae vacate the galls in late September, work their way into the litter, and construct cocoons in which they overwinter. Pupation occurs the following May. Trees from 2 to 30 ft tall are attacked; lower branches are attacked the heaviest. Large galls kill buds, twigs, and entire branches. Small galls leave deeply indented branch scars and deformed limbs.

The Iowa Insect Survey has, for more than ten years, been studying the seasonal and geographic distribution of Iowa insects. The records are card indexed and come from various sources, chief of which is the survey collection made up by frequent collecting trips covering the entire state. In this way at least some preliminary work has been done in each of the 99 counties of Iowa. Many of these counties have been rather thoroughly worked for special groups.

The Scutacaridae are very little understood. Paoli divided the genera chiefly on the basis of presence or absence of ungual hooks on tarsi I and IV. This is patently a superficial and non-phylogenic character. Within a genus all grades of reduction of unguis are to be found so that it is quite conceivable that species without unguis may belong to genera with unguis. Furthermore in each genus one may find, if Paoli's figures are correct, species with dorsal segments, ranging in number from four to six. Yet number of transverse plates, usually regarded as an indication of number of somatic segments, is certainly a more fundamental character than ungual reduction. On the other hand it is quite difficult to determine with certainty the total number of transverse plates in some species. My experience leads me to regard the total number of plates as four, each bearing four bristles. At present this character will have to be disregarded.

Among the Ephemeridae which the senior author reared at Ithaca, N.Y., from 1913-1915, were two very common species of the genus Heptagenia. The nymphs of both of these species are described by Needham in Bulletin 86. N. Y. State Museum, and figured in plate 9. Extensive rearings, about 50 in all, show, however, that the nymph described as Heptagenia sp. 3 and illustrated in Fig. 4 of plate 9, is that of Heptagenia interpunctata, while the nymph described for that species and illustrated in Fig. 3 of plate 9 appears to belong to a new species which we here describe.

The purpose of the present paper is to describe two new species of Bolbocerosoma and to figure the genitalia of the North American species of this genus. It therefore supplements the paper of Dawson and McColloch (Can. Ent., LVI, 9-15).

The mosquitoes Anopheles barberi, Orthopodomyia signifera, and Orthopodomyia alba are recorded for the first time in Canada. All three species were found breeding in the water-filled rot cavities of trees in the deciduous forest of Point Pelee National Park, Ontario. Attention is drawn to the probable rarity of these mosquitoes in Canada and their conservation is recommended.

Male.—Length, 10.5 mm. Black with yellowish markings. Head transverse, as wide as thorax, about twice as wide as long when viewed from above; face above the antennæ, and vertex, polished, impunctate, without apparent sutures and with sparse blackish pubescence; the cheeks and under surface with pubescence more dense; clypeus polished; palpi slender; antennæ as long as head and thorax, rather stout, eighteen-jointed, segments subequal; eyes small but prominent; ocelli small, in a triangle on a line with the posterior margins of the eyes. Thorax rugose with coarse, irregular punctures, those of the pleura and pectus smaller and more numerous; posterior angles of prothorax yellow; legs rather slender, coxa and femora black, remainder yellow, the tips of tibiæ and tarsi somewhat dusky; wings subhyaline, with dark stain covering marginal cell and extending slightly beyond each end of it, stigma and costal nervures black, remaining nervures reddish, second and third submarginal cells subequal; scutellunl abruptly rounded posteriorly, postscutellum yellow, prominent, subpyramidal, notched at apex, in suture on each side several deep shining foveæ; metathorax very short and rounded at sides, without prominent angles, a small yellow spot on each side. Abdomen polished, impunctate, apparently with six segments; second segment as long as all the following and with a yellow central band, or elongated spot on each side; a yellowish spot at lateral base of segments 3 and 4, very faint on the latter; venter slightly pubescent, with double row of yellow spots on segments 1 to 5, largest on 2nd.

A 2-year field study was carried out to determine densities and stage-specific survival of eggs, second- and third-instar larvae, prepupae, pupae, and adults of Strobilomyia appalachensis Michelsen in a black spruce, Picea mariana (Mill.) B.S.P. (Pinaceae), seed orchard located in New Brunswick, Canada. Trends in stage-specific survival were similar for both years. Most individuals died during the second-instar stage, we suspect mostly because of failure to establish. The lowest stage survival occurred during the prepupal and pupal stages, due primarily to predation by ground-dwelling invertebrates.

An unusual infestation of the pill beetle, Cytilus alternatus Say, occurred in the Provincial Forest Nursery at Gogama in northern Ontario in 1967. Although Craighead (1950) mentions species of Byrrhus, a closely related genus, as pests in nurseries, no previous record of injury to seedlings by C. alternatus could be found. Two incidental collections of C. alternutus, however, had been made previously in Ontario when a few pupae were collected in the Chapleau Forest Nursery in 1965 and a single adult was taken on St. Joseph Island in 1954. Members of the family Byrrhidae derive their common name, pill beetles, from their oval shape and their ability to “retract” their appendages when disturbed.

The number of male and female first generation Panonychus ulmi (Koch) were recorded from 13 apple orchards representing widely different levels of mite infestation on four different varieties. The average percentage of males was 27.5. Statistically significant differences were found among orchards, varieties, observers, and their interactions. No relationship between sex ratio and population density was evident.

Two-sample and four-sample methods of assessing insecticidal control efficacy are explored. Respective indices of survival and mortality including methods of constructing confidence intervals and minimizing bias are discussed. Procedures for determining the number of samples required for specified statistical limits are presented

Cattle grubs, first-instar larvae of Hypoderma bovis (L.), were removed from nine slaughtered heifers. Two of these heifers had previously been treated with coumaphos, three with Ruelene, and two with trichlorfon. The remaining two heifers were not treated with insecticides and served as sources of control grubs. The grubs, after removal from the hosts and fixation in formalin, were incubated with one of the two cholinesterase substrates, acetylthiocholine iodide or 5-bromoindoxyl acetate. Cholinesterase was completely inhibited in the central nervous systems of the grubs whose hosts were treated with Ruelene. This inhibition was also virtually complete in grubs from heifers treated with trichlorfon and was usually complete in those from the heifers treated with coumaphos. This is presented as histochemical evidence that the three systemic insecticides inhibit the cholinergic enzymes in the grubs, thus causing them to die while still in the body of the host.

An investigation was made of the impact of a series of environmental catastrophes upon herbivore population regulation through density-dependent genetic feedback interactions with simulated plants. Mean density and amplitude of fluctuation of the herbivore in the control system (only susceptible alleles in the plant population) were higher than in the genetic feedback system (3 resistant alleles and 3 susceptible alleles in the plant population). Mean density and amplitude of fluctuation of the herbivores in the catastrophic system (only susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes) were lower than in the control and genetic feedback systems, but both mean density and amplitude of fluctuation were higher than in the genetic feedback and catastrophic system (3 resistant and 3 susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes). The results of this experiment suggest that genetic feedback can exert a controlling influence in population dynamics even in systems where environmental catastrophes are a common occurrence.

The full-grown larva of Pristiphora acidovalva Wong, a newly recognized sawfly on willow, is described and the occurrence of the species in Ontario is discussed.

1. Aradus concinnus, Bergr.— Female: Fifth ventral segment as long in the middle as at the sides, with a transverse obtuse-angulated keel a little in front of the almost straight middle part of the apical margin, this keel at the ends coalescing with the apical margin, apial angles of the segment reaching a little beyond the slightly rounded apical margin of the middle part of the sixth ventral segment, which is broader than long, apical angles of this segment nearly reaching apex of second genital segment, which does not project behind apex of abdomen and is half as long as the transverse first genital segment, this more than twice as broad at base as at apex, apical gential segment, this more than twice as broad at base as at apex, apical genital lobes shortly prominent beyond apex of abdomen, somewhat distant interiorly, inner margin rounded, apical margin oblique, notched before the middle, dorsal gential segment broadly rounded at apex.