This paper is one in a series on sampling techniques used in population studies of the larch sawfly (Ives, 1955; Ives and Prentice, 1958). The technique has been developed to provide bases for comparing the intensity of sawfly infestations in stands of different compositions, and for studying the effect of the insect upon its host. A preliminary study demonstrated the feasibility of developing a sampling method for estimating foliage weight, but also indicated that the foliage weight increased as the season progressed (Ives, 1958). Foliage sampling in stands infested by the larch sawfly must be completed before defoliation becomes prevalent, and the foliage weight may increase considerably after sampling. In 1956 an intensive sampling program was carried out on tamarack in the Whiteshell Forest Reserve, Manitoba, to determine the sample size needed to obtain statistically acceptable estimates of foliage production and to study the nature of changes in foliage weight during the season.

Linaria vulgaris Mill., known commonly as toadflax or butter-and-eggs, is worldwide in its distribution but is a serious weed only in the Canadian provinces of Alberta, Saskatchewan, and Manitoba (Zilke and Coupland, 1954), where it is increasing in importance (Beck, 1954; Carder, 1956; Forbes, 1957). Smith (1956) correlated its relative insignificance as a weed in the other provinces and in the northwestern United States with the occurrence of the curculionid beetle Gylmnaetron antirrhini (Payk.). Investigations on this and other insects that feed on toadflax and an evaluation of their possible use as biological control agents are reported in this paper; also included are some observations on the weedand its natural enemies made since 1950 in all provinces west of Quebec and in the northwestern United States.

Many authors observed that mosquitoes respond to a large variety of artificial sounds (for references see Roth. 1948). Efforts to attract males of Aedes aegypti (L.) by play-back recoridings of the flight sound of the female have met with moderate success (Kahn et al., 1945; Offenhauser and Kahn, 1949; Kahn and Offenhauser, 1949). Roth (1948) demonstrated that males of A. aegypti approached the sounds of tuninh forks and sine sounds from a speaker. He also determined the upper and lower limits of frequencies that stimulated males, but in these experiments he did not use attraction to the source of the sound as the criterion of response, but the “seizing and clasping”reaction. He exposed the maIe mosquitoes in cages, three inches by three inches by one inch, placed against a box that housed a loud speaker. Under these conditions the mosquitoes had little opportunity to fly to orient themselves toward the sound source. Moreover the sound used was of such intensity (108 db at 2½ inches) that the whole cage vibrated, so that at least part of the response was undoubtedly caused by vibration of the substratum on which the mosquitoes rested. Sounds of such intensity do not normally occur in the natural environment of the mosquito. Moreover, the “seizing and clasping” response does not occur until the male approaches the female in response to sound or other stimulus. If the place of sound in the attraction of thc males is to be studied, the primary response, that of approach, should be the criterion and the amount of sound used should bear a reasonable relation to that occurring in nature.

In 1954, the use of Methocel (methyl cellulose) as a sticker in laboratory studies of bacterial pathogens was described (1). Although satisfactory for laboratory use, Methocel is not practical for field use because of its solubility in water. In a field experiment 1½ inches of rain in two hours reduced by 80 per cent the residual count of bacteria applied as a suspension in Methocel. In a search for a more satisfactory sticker for field use, colloidal dispersions of vinyl chloride polymers and copolymers in water have been tested. These trials have been sufficiently encouraging to justify a preliminary report of the results.

It is generally agreed that insects whose larvae feed on plants do not increase to the larval food limit except in sporadic and unusual cases. In the few detailed studies which have been made, as, for example, Varley's (1947) study of the knapweed gallfly, the evidence suggests that the insects are held in check by parasites and predators. Andrewartha and Birch (1954) are of the opinion that shortage of food is probably the least important factor in limiting the numbers of animals in a natural population. On the other hand, they have pointed out (p. 489) that while it is unusual for an extensive population to consume all or most of the stock of food in its area, it does not follow that the amount of food is rarely of major importance in determining the numbers of a natural population. Several examples (p. 492) were given in which shortage of food was chiefly responsible for failure of population increase even though the absolute supply seemed adequate. In these cases local supplies were exhausted and the chance of finding fresh supplies depended upon the distribution and abundance of food and the powers of dispersal of the animals. In other words, the food was inaccessible relative to the animals' capacities for dispersal and searching.

I am indebted to Mr. J. Powell, University of California, Berkeley, for the privilege of studying a small but interesting collection of Pyralidae, made by him in the Sierra San Pedro Martir, Lower California, May 28 to June 3, 1958.As records from this region of Mexico are scarce, I take pleasure in publishing a list of the species.

Pyraustinae

Nomophila noctuella (Denis and Schiffermüller) . Nine specimens: La Grulla, 6500 ft.; La Encantada, 7000 ft. Identical with North American specimens passing under this name.

The Douglas-fir beetle, Dendroctonus pseudotsugae Hopk., is a constant threat to Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests because of its ability to kill large quantities of this important timber tree. In the search for more effective control of this pest the need for experimental insects frequently exceeds the supply from natural sources. Laboratory rearing can alleviate this shortage.

1927–Needham – Ann. Ent. Soc. Amer., 20: 108.

1935–Traver – Biol. Mayflies, 565 (hecuba group).

1954–Edmunds and Traver – Proc. Ent. Soc. Wash., 56: 238.

1954– Demoulin – Bull. Ann. Soc. Ent. Belg., 90: 324.

The subgenus Timpanoga of the genus Ephemerella contains but a singIe species,Ephmerella hecuba Eaton. Needham (1927) derived the name for this subgenus from Mt. Timpanogos in north central Utah, after collecting specimens of Ephemerella hecuba in the nearby Provo River. He based the subgenus on the nymph which shows remarkable morphological distinction with its broad entire frontal shelf and its extremely flattened body.

During studies on the aster yellows virus in the Niagara Peninsula of Ontario, the dryinid parasite Epigonatopus plesius (Fenton), has been observed since 1956 on the nymphs and adults of the six-spotted leafhopper, Macrosteles fascifrons (Stål). During 1956 adult females of E. plesius reared from this host were identified by Mr. K. V. Krombein of the U.S. National Museum, Washington, D.C. Dr. W. R. M. Mason (1957) Entomology Division, Ottawa, wrote, “This is a very rare species. There are only two collections in Washington and only yours in the Canadian National Collection”.

The pales weevil, Hylobius pales, was described in 1797 by Herbst (9), but it was not until 1916 that its importance in limiting the regeneration of white pine, Pinus strobus L., in cut-over areas was established by Carter (4). H e reported that up to 70 per cent of young reproduction trees might be killed by adults feeding on thc bark of young seedlings during the first two years following clear cutting of white pine. He concluded that it was unwise to plant white pine during the two seasons follouring cutting because seedlings in the vicinity of the stumps, in which the Weevil breeds. would be subjected to heavy feeding, and the resulting loss of trees would produce open areas in the planting. In 1921, Peirson (10) recorded in broad terms the seasonal history, distribution, host plants, habits,and control of the weevil, based primarily on a study of the insect in Massachusetts. More recently, Beal and McClintick (1), Bess (2), Savely (11), Sentell (12), and Wells (16) have emphasized the continued importance of the weevil as a forest pest and have recorded its presence in most of the United States east of the Mississippi and north of Florida, and in Canada from Nova Scotia to Manitoba. Friend and Chamberlin (8) and Ebel and Speers (5) have discussed population levels of the weevil in relation to cutting practices, and Speers (13, 14, 15) has discussed its control through the use of sprays and dips.

Although the leafhopper Colladonus clitellarius (Say) was found by Gilmer (1954) and Thornberry (1954) to be a vector of eastern X-disease virus of peach and cherry, little has previously been reported concerning the life-history or rearing of the insect. Gilmer (1954) stated that he did not know the host plant of the nymph and that collections of adults as early as June 3, 1953, and as late as October 22, 1951, suggested strongly that the insect may overwinter as an adult in New York State. Phillips (1951) found the species in sour-cherry orchards in the Niagara Peninsula of Ontario

Myzocallidium riehmi (Börner) was collected from sweet clover at Creston in June, 1957. This is the first time this aphid of potential economic importance has been identified from British Columbia. It occurs throughout the United States (Russell, 1957); in Ontario, Ottawa being near the northern limit of its range (W. R. Richards, in litt.); and was identified for the first time from Manitoba in 1956 (Bird and Robinson, 1957)

Aphids of the species herein described as new can be readily distinguished from all other species in the genus Cinara by the unusual length of the unguis. The feeding site is also characteristic; this is the only species in the genus known to feed on the roots of Pinus banksiana.

The species was first collected in 1956 at Lac La Ronge, Saskatchewan, by B. B. McLeod, of the Winnipeg Laboratory. In 1957 it was found by the authors at Cedar Lake, thirty miles north of Vermilion Bay, Ontario, where observations on the life history of the species were carried out.

On January 10, 1958 a collection of 20 galls was made from a rose bush in an abandoned brickyard bounded by Cheapside, Taylor, Victoria and Adelaide Streets at London, Ontario. This was the same site in which collections of galls were made from goldenrod and willow by Judd (1953, 1958). Collections of flowers and leaves from the rose bush were made later in the year on June 20 and fruits were collected on September 14. From examination of these the bush was identified as Rosa canina L. by Dr. F. H. Montgomery, Department of Botany, Ontario Agricultural College, Guelph, who retained specimens of the plant for the herbarium of that institution. Specimens are also retained in the writer's herbarium (sheets 603, 604). By using keys in Felt (1940) the galls were identified as mossy rose galls or rose bedeguars caused by the cynipid wasp Diplolepis rosae (L.). The galls were roughly oval and were clothed with a furry covering of flexible filaments, thus resembling galls of this species figured by Connold (1902) and Felt (1940). The 20 galls ranged in size from l¼ in. × 1¼in. to 3 in. × 2½ in. Connold (1902) records the average dimensions of a mature gall to be 35 mm. and Felt (1940) reports diameters up to four inches. Callan (1944), Connold (1902) and Muesebecli et al, (1951) report that this gall has been introduced from Europe into North America and occurs habiyually on the dog-rose, Rosa canina L., a shrub which itself has been introduced into North America from Europe (Fernald, 1950).

Carvalho and Usinger (1957) divided the North American genus Dacerla Signoret, 1881, into two. Dacerla now contains those species with a spinelike projection on the posterior margin of the pronotum, and Paradacerla Carvalho and Usinger contains those species wqithout a spinelike projection.

In this paper Paradacerla species and Dacerla mediospinosa are compared, especially concerning the genitalic characters, and a new species, P. hirsuta, is described. Distinguishing external characters of the species and a key toParadacerla are provided

Aphidecta obliterata (L.) is a common predator on conifer-infesting adelgids and aphids in Western Europe, including Scandinavia and the British Isles (Wylie, 1958b). The life cycle in Europe and descriptions of the various stages have been published (Weise, 1892; Portevin, 1931; Van Emden, 1949; Van Dinther, 1951; Wylie, 1958a). Beginning in 1941 several attempts have been made to introduce this species into Eastern Canada against the balsam woolly aphid, Adelges piceae (Ratz.). The initial liberations from England and Germany were apparently unsuccessful due to the inability of the insect to survive the Canadian winter conditions. Later collections were made in Sweden, Czechoslovakia, and Switzerland (Table I) from areas where the winter conditions more closely resemble those in Canada. These liberations also proved unsuccessful. The present paper brings together all available information on the liberations and related experiments olbtained during the liberation years.

The genus Isonychus contains about 60 described species, largely from Central and South America. None have been recorded previously from the United States. The species described below from southern Arizona extends the known range of the genus about six or seven hundred miles northward.

The genus is placed in the Macrodactylini and may be briefly characterized as follows: surfaces of vertex, pronotum, scutellum, and elytra covered with setae; elytra feebly striate; setal color pattern usually present on elytra; fore tibia bidentate; all tarsi with two claws, each of the latter cleft at tip and with a small basal tooth; one tibial spur on each fore leg, two spurs on each mesothoracic leg in both sexes and two tibial spurs on each metathoracic leg of the female, spurs lacking or single on the metathoracic legs of the male; fore and middle coxae contiguous or very narrowly separated.

The poplar sawfly, Trichiocampus viminalis Fall., is indigenous to Europe, where it is common and widespread, but is also prevalent in the north-eastern United States, Eastern Canada and British Columbia. For the past five or six years it has caused serious defoliation to Populus nigra and P. deltoides in the vicinity of Quebec City.