Female. Frons slightly produced, with a rudimentary median carina. Head, body and forewing above pale luteous, hind wing above and under side whitish. Abdomen above with narrow white basal band and with three or four obscure blackish-powdered mid-dorsal spots. Fore coxa, femur and tibia brown anteriorly. Forewing above with narrow, obscure, dark, irregularly dentate ante- and post-medial lines. Antemedial oblique outward to origin of Cu1, then sharply angled and oblique inward to inner margin. Postmedial nearly parallel to outer margin, weakly indented along submedian fold. An hourglass-shaped mark at the end of the cell. All these markings surrounded by faint fulvous clouding. Outer margin with minute black dots at ends of veins. Fringe concolorous. Hind wing with one or two dark dots in submedian fold and with black terminal dots at the veins. Under side of forewing with lunate discocellular mark and anterior half of postmedial line conspicuously dark.

This paper offers a taxonomic treatment of the North American species of the genera Niptus Boieldieu (1856, pp. 290, 662), Epauloecus Mulsant and Rey (1868, pp. 49, 198), and Pseudeurostus Heyden (1906, p. 424), which was proposed as a new name for Eurostus Mulsant and Rey, 1868, not Dallas, 1851. Six species are considered, Two of these are treated in Fall's revision of the North American Ptinidae (1905, pp. 107-108). Two others are Old World species that were discovered more recently in Canada, and two species are dcscribed as new. All of the species belong to Niptus in the sense of Fall's revision, which this paper supplements. Three of the six species are imported minor pests and are known in America only from buildings, where they breed in organic matter of various kinds. The others are native, outdoor species of the wesrern United States. Hinton (1941, pp. 339-344) has described and figured the pest species and has summarized the literature on their habits.

Entomologists, like research workers in other fields, frequently wish to determine whether the percentage of individuals having a certain attribute (e.g., % eggs parasitized) is associated with some other variable, which may be either qualitative or quantitative. The numbers of individuals observed with and without this attribute are recorded for each category of the other variable. A test is made of the hypothesis that the true percentage or proportion of individuals with this attribute is the same in each category. One of the methods commonly used for this purpose is the x2 test of independence. If rhe calculated x2 exceeds a specified level of significance, the hrpochesis is rejected; otherwise it is accepted. The test is described in most books on statistical methods, e.g., Goulden (1952).

Collyria calcitrator (Grav.) is an important parasite of the wheat stem sawflies Cephus pygmaeus (L.) and C. (Trachelus) tabidus (F .) in Europe (Salt, 193 1). It was imported from England and released against the wheat stem sawfly, Cephus cinctus Nort., in the Prairie Provinces, especially Saskatchewan, from 1930 to 1939. One of its usual hosts, the European wheat stem sawfly, C. pygmaeus, first reported in Ontario in a meadow near Ottawa in 1887 (Harrington, 1890), was first recorded as damaging wheat in Ontario in the counties of Hastings, Prince Edward, and York in 1938. I t was a serious pest in New York and Pennsylvania in the early 1920's (Ries, 1926). As C. cinctus was a major pest of wheat in Western Canada and C. pygmaeus a pest in New York and Pennsylvania, the discovery of moderate to heavy infestations of C. pygmaeus in several localities in south-central Ontario in 1939 by Mr. G. H. Hammond, Entomology Field Station, Marmora, caused concern about the future importance of the sawfly as a pest of wheat in Ontario. C. calcitrator was being imported from England for release against C. cincctus in Western Canada at the time and advantage was taken of the opportunity to release the parasite in Ontario as a possible aid in control.

The genus Linosta was described by Möschler (1881: 433) for the single species L. sinceralis Möschler from Surinam. There have been few subsequent published references to the genus, but in most collections it stands in the Schoenobiinae. Amsel (1956) surveyed the structural characters and noted that the genus did not fit very well into the Schoenobiinae or any other subfamily and that it would possibly require its own subfamily “Linosterinae”, but he left it in Schoenobiinae for the time being. In my opinion the group is sufficiently distinguished from the Schoenobiinae by the absence of proboscis, of maxillary palpus, of chaetosema, and of tubular 1st A of primary, as well as by the different tympanic and genital striucturc. The absence of the maxillary palpus would place the genus in Chrysauginae, but the joining of the tympanic bullae and the presence of a definite praecinctorium (new term for tablier of Guenée = Schürze of Lederer = Kielhäutchen of Amsel) rule this out. The group obviously belongs in the basal part of the crambine-pyraustine complex; the actual affinity appears to be to the Cybalomiinae (new subfamily, type genus Cybalomia Lederer, characters of Crambinae, but with chaetosema absent). The male genitalia agree well with those of Cybalomia and Stiphrometasia, especially in the close association of the base of the gnathos with a strap-like sclerite connecting with the costal articulation of the valve. Also the tympanic structure is closely similar to that of Stiphrometasia and furthermore to that of Thyridophora, which has a fovea and associated stalking of R5, and M1, just as in Linosta, and which also lacks the proboscis.

Grammonota Emerton, 1882, is one of the many uniform genera that constitute the large and complex family Erigonidae. All of the 28 species and one subspecies recognized by the present writer are American in range, and representatives occur from southwestern Alaska and James Bay in the north to Central America and the West Indies. A few species are arctic-alpine, or are restricted to the Pacific coast, but most occur east of the Rocky Mountains from southern Canada to the Gulf States.

The senior author collected several nearly mature lepidopterous larvae found tunnelling in ripening strawberries at Saanich, Vancouver Island, B.C., on June 10, 1957. From larvae reared on fruit in cages in an insectary, six moths emerged, two each on July 15, 18, and 22. These six and another individual collected in flight were identified as the omnivorous leaf tier, Cnephasia longana (Haw.).

Entomologists interested in population dynamics have devoted considerable attention to the numbers of eggs laid by various species of insects, the mortality and non-viability of eggs, and mortality in young larvae; but there is another aspect of the problem which has received less attention than it deserves. This is the necessity for females to place their eggs sufficiently close to an adequate supply of food to insure the growth and development of the F, generation. Fulfillment of this requirement is particularly important for those species whose larvae are restricted feeders, that is, monophagous or oligophagous. It is generally assumed that the continued existence of a species is evidence that the eggs are always properly placed. As a consequence of this assumption very few quantitative studies have been undertaken, with the result that the contribution of the adult's behaviour to the degree of survival in larval populations is unknown. The following field studies were undertaken to supply some information on this score.

Many new species of Typhlodromus were described in recent years and these can readily be assigned to the species groups established by Chant (in press). Recently I received some slides of mites collected by Dr. Stanley Flanders, Citrus Experiment Station, Riverside, California, in Hong Kong in 1953. These mites are of the subgenus Typhlodromus as defined by Chant (1957), of a hitherto undescribed species that does not fall into any of the groups listed and that is of particular importance to those interested in the systematics of the Phytoseiidae.

Resistance in plants to the cabbage maggot, Hylemya brassicae (Bouché), has not been investigated extensively. Glasgow (1925) and Whitcomb (1944) compared the percentages of infestation of species of cruciferous crops and varieties of cabbaage. Whitcomb (1944) attributed differences in degree of injury among 13 cabbage varieties t o resistance in the plants rather than to repellent action during oviposition. He observed that the faster-growing varieties of cabbage were more susceptible to injury. The investigations reported herein were designed to determine if rutabagas had resistance to the cabbage maggot.

During November, 1958, I studied the Provancher types of Ichneumoninae in the Provincial Museum of Quebec. My work was very much facilitated by the kind assistance of subdirector Noel-M. Comeau, who has arranged the once badly neglected historical specimens in a most exemplary way, securing them against any further damage as well as saving the time of the visiting specialist. I have only to regret that the revision of all Provancher types, which Mr. Comeau has accomplished by many years' endeavour, is not yet published and therefore not available yet to scientific workers.

In May, 1956, large numbers of small caterpillars were found on Japanese plum trees in an orchard near Queenston in the Niagara Peninsula, Ontario. The owner stated that he first noticed them in 1955 when they got on his clothes while he was cultivating the orchard. In June, 1956, the caterpillars were also found on ornamental plum, Prunus cerasifera Ehrh. var. pissardii Koehne, in nurseries at Niagara-on-the-Lake and Fonthill by nursery inspectors.

No research has previously been conducted on gall aphids on poplar in Alberta. Strickland (1953) published records of some of these aphids in his list of Hemiptera of Alberta. Manson (1931) mentioned that noctuids fed in galls of Pemphigus populitransversus Riley.

In the United States, several workers have reported on these aphids. Palmcr (1952, pp. 358-372) published a key to and some bioiogical notes on several species of the genus Pemphigus and related genera. Maxson and Knowlton (1929) gave considerable information on the life-history and classification of the tribe Pemphigini. Maxson (1923) and Hottes and Frison (1931) published keys to the same tribe. Essig (1926, pp. 259-261), Gillette (1913). Gillette and Bragg (1915), Jackson (1908), Oestlund and Hottes (1926), Patch (1913), Swaine (1919), and Williams (1910) also reported on some of the gall aphids on poplar.

In the genus Anoplodera two species, mutabilis Newman and aspera LeConre, represent a small, distinct group. A thirdspecies, previously unrecognized and closely related to aspera, has been noted in material submitted for identification. The present description and distributional notes are based on material in the California Academy of Sciences, the Canadian National Collection, Cornell University, Ohio State University, the United States National Museum, and the personal collections of Dr. J. N. Knull, Ohio State University, Columbus, Ohio, and Mr. C. A. Frost, Framingham, Mass. I wish to thank Dr. Knull for examining some of the eastern specimens that have been confused with aspera; he concurred that they represented an undescribed species

During studies at Ottawa on the physioloLgy of the onion maggot, Hylemya antigua (Meig.), 29 per cent of 2,320 puparia that had been collected in muck soil at Ste. Clothilde, Que., in the autumn of 1957 were parasitized by the braconid Aphaereta pallipes (Say)2. There are few reports of this insect's parasitizing Diptera in Canada and none on its life-history orbehaviour. Hammond (1932) found it in first-generation puparia of the onion maggot at Ottawa. Wishart (1957) reared it from puparia of the cabbage maggot, Hylewyn brassicae (Bouché), collected from St. Martin and St. Rose, Que. Notes on the biologies of two other species of Aphaereta have been published by Graham-Smith (1919) and Evans (1933), the former on Aphaereta cephalotes (Hal.) and the latter on Aphaereta minuta Nees. Both species are parasites of carrion-infesting Diptera.

Semium was described bv Reuter (1875) and placed in the division Cyllocoraria of the subfamily Capsina. Reuter (1910) later chanped the subfamily Capsina to Heterotomina, and the division Cyllocoraria to Halticaria. Van Duzee (1916) changed Reuter's Heterotomaria to Orthotylinae, and placed Semium in the division Orthotylaria, tribe Orthotylini. Knight (1923) proposed the tribe Semiini for the Genus, but Carvalho (1955) rejected this arrangement and placed the genus in the Orthotylini. Studies on the female and male genitalia by Slater (1950) and Kelton (1959) suggestee that the genus is referable to the Phylinae. In this paper the genus is transferred from the Orthotylinae to the Phylinae. tribe Phylini, on the basis of the male and female genitalia and the tarsal claws.

During the winter of 1957-58 larvae of the tent caterpilIars Malacosoma pluviale (Dyar) and M. americanum (F;.) were reared to provide material for tests on the spore-forming bacterium reported by Bucher (1957). AS there is little published information on winter rearing of sent caterpillars, except that of Sippell (1952) on M. disstria Hbn., the technique is given below.

This is a report on field observations and experiments on the life-history of the onion maggot, Hylemya antiqua (Meig.), conducted from 1955 to 1958 in sandy and organic soils of southwestern Quebec. The dates of emergence of adults, the number of generations, the percentage of pupae entering diapause in each generation, and the relationship between diapause, air temperature, and precipitation were recorded.

The fluctuation of an animal's numbers between restricted limits is determined by a balance between that animal's capacity to increase and the environmenta1 cheks to this increase. Many authors have indulged in the calculating the propressive increase of a population when no checks nrerc operating. Thus Huxley calculated that the progeny of a single Aphis in the course of 10 generations, supposing all survived,would “contain more ponderable substance than five hundred millions of stout men; that is, more than the whole population of China”, (in Thompson, 1929). Checks, however, do occur and it has been the subject of much controversy to determine how these checks operate. Certain general principles—the density-dependence concept of Smith ( 1955) , the competition theory of Nicholson (1933)—have been proposed both verbally and mathematically, but because they have been based in part upon untested and restrictive assumptions they have been severelv criticized (e.g. Andrewartha and Birch 1954). These problems could be considerably clarified if we knew the mode of operation of each process that affects numbers, if we knew its basic and subsidiary components. predation, one such process, forms the subject of the present paper.