Three species of caterpillars commonly attack cabbage at Ottawa, namely, the imported cabbageworm, Pieris rapae (L.), the larva of the diamondback moth, Plutella maculipennis (Curt.) and the cabbage looper, Trichoplusia ni (Hbn.). All three species are readily controlled with DDT sprays or dusts but the timing of the applications is imporrant. Growers sometimes begin dusting or spraying too early, wasting one or more applications, or they delay the first application until mid-August, when severe damage has already occurred. This paper is a report on four seasons' experiments at Ottawa, 1947 to 1950, to determine the number and timing of applications of DDT required for control of caterpillars on late cabbage.

In revising the genus Triaspis Haliday, as found in North America north of Mexico, the author studied an undescribed species from Mexico. This form is a parasite of Apion godmani Wagner, a weevil of economic importance. This paper provides a name and a description for this new parasite.

The author is most grateful to Dr. V. S. L. Pate of Cornell University for his helpful criticism of the manuscript, and also to Mr. C. F. W. Muesebeck of the U.S. National Museum for the loan of material, and to Dr. Arthur C. Smith of Cornell University for the specimens collected while he was studying the biology of the host in Mexico.

The frequent failure of parasite development beyong the immature stages during insectary rearing work often results in incomplete qualitative and quantitative data on insect parasites. Keys to the larval and pupal stages are therefore an extremely useful aid in completing the picture in a study of A parasite complex.

The following illustrated key makes it feasible to obtain reasonably accurate specific determinations of the puparia of the dipterous parasites of the spruce budworm, Choristoneura fumiferana Clem., that occur in Canada. The writer gratefully acknowledges the inspiration and co-operation of A. R. Brooks during the preliminary preparations for the key. The illustrations were executed by Miss M. MacKay (Figs. 1-14) and R. Sugden (Fig. 15). Each figure illustratis the following: (a) posterior aspect of a puparium showing the location of the stigmal plates and the anal aperture, and any protuberances that are present; (b) one stigmal place and the stigmal slits; (c) lateral aspect of the outline of a puparium.

The male of Ixodes soricis Gregson was discovered at Silver Creek, British Columbia, in 1948 (Gregson, 1949). The tick was found with its hypostome fully inserted into the lateral body wall of a partially engorged female of the same species. It was not described because the specimen in situ represented an interesting example of either accidental parasitism (Anastos, 1948), or more likely an unsuccessful attempt at copulation, since it is questionable whether the males, like those of some other species of Ixodes, ever feed. The recent discovery, however, by the junior author, of another specimen, in a collection of ticks from a shrew taken at Seattle, Washington, permits the following description of the male of this species.

In May, 1948, numerous malformed buds were collected from young spruce trees at Fredericton, N.B. These enlarged buds were about 7 mm. long and 4 mm. in diameter, with lateral scales reflexed and their rosette-like apices loose and open. Dipterous adults emerged in a few days and their identification as Rhabdophaga swainei Felt was confirmed by G. E. Shewell, Systematic Unit, Division of Entomology, Ottawa.

The only references in the literature are Felt's (1) original description of the adults and a mention of the gall by the same author (2).

The following notes are based on field observations made at intervals through 1948 and early 1949 near Fredericton, N.B.

Literature on grasshopper control published hetween 1930 and 1942 stressed the desirability of applying poisoned bait when grasshoppers begin their first main feeding period of the day. Such pubiications include those by Parker (1930). Parker, Walton, and Shotwell (1932), Criddle (1932). Ruggles and Aamodt (1938), and Bird (1940). Parker (1930) found that the lesser migratory grasshopper, Melanoplus mexicanus mexicanus (Sauss.), fed sparingly on baits at air temperatures between 55°F. and 63°F., more actively between 64°F. and 67°F., and most actively between 68°F. and 78°F. A rapid decrease in feeding occurred when air temperature rose above 80°F. or the soil surface temperature above 113°F. Much the same relationship held also for the clear-winged grasshopper, Cammula pellucida (Scudd.). On the basis of such observations it was decided chat an air temperature of 68°F. might be classed as optimum for beginning the application of bait. Parker did not, however, indicate the degree of mortality resulting from such feeding; the other writers gave no experimental data.

Leafhoppers of the genera Orocastus and Auridius are locally abundant in grassland regions in Western Canada. They are small insects, the males golden yellow and the females stramineous in colour. The two genera are distinguished from each other by characters of the internal male genitalia. The species are distinguished primarily by these characters and by the form of the seventh sternite of the female. There has been some confusion between the species, partly because the sexes were wrongly associated by some authors and partly because the extent of the individual variation was not appreciated fully. The following are descriptions and illustrations of the distinctive character; of the four species found in Canada, with notes on the distributions and variation. One species new to science is described and one species is reduced to synonymy.

In investigations on the life-history of the onion maggot at St. Jean, Que., in 1951, a few specimens of a dipterous predator were found in the rearing cages in the laboratory. They were feeding voraciously on the adults, destroying a colony of nearly 300 flies within two weeks.

Specimens were identified by Mr. A. R. Brooks, Systematic Entomology, Division of Entomology, Saskatoon, Sask., as Coenosia tigrina (F.). Mr. G. E. Shewell, Systematic Entomology, Division of Entomology, Ottawa, has stated that nothing is known in Canada about the life-history of this species, but that it is apparently well known as a predator in Europe and that B. M. Hobby has published a long list of species on which it preys, including many anthomyiids.

Length (male and female) 4.5 mm. Width 1.2 mm. Face slightly convex, vertex poinced, slightly more than right angled, 1½ times wider between the eyes than length at middle line. Pronotum twice as wide as long. Male plates spoon-shaped, curving upward at the tips. Female seventh segment evenly rounded at the sides, broadly excavated at the centre, with the usual strap-shaped projection, at the tip of which is a small V-shaped notch.

The use of potassium hydroxide solutions for clearing minute insect specimens, or portions of large ones, is a well-known and widely used procedure. Extreme care, however, is necessary to provide rapidly the exact degree of transparency in the subject. To provide for these requirements an economical heater was designed to warm a micro-culture slide bearing a few drops of clearing solution. The specimen is immersed in the cold solution on the slide, and the slide is then placed on the heater. The requisite amount of current is supplied to the heating element and clearing of the specimen to the exact degree desired can be obtained in a short time while the process is observed through a binocular dissecting microscope.

General.—The purpose of this paper is to analyse a sampling method devised to assess larval populations in an outbreak of the lodgepole needle miner, Recurvaria milleri Busck (Busck 1914, Hopping 1945).

The problem of developing an adequate sampling method is intimately concerned with the life-history of the insect, the region of the outbreak and the nature of the forest stand in which the outbreak occurs. In sampling most defoliator populations the problem is made more difficult by external feeding and wandering habits, hence it is usually done in some relatively inactive stage at a fixed time. de Gryse (1934) describes the problems inherent in sampling these insects. The needle miner, however, is fixed in its location for most of its life-cycle and is therefore readily obtainable for study. The problem here is reduced to a statistical one, that of obtaining an acceptable sample i.e. within suitable error limits with due regard for existing variables.

In 1945 a field experiment was designed at the Lethbridge laboratory to augment data on the effect of the time of seeding on infestation by the wheat stem sawfly, Cephus cinctus Nort. At that time one of the recommendations for the control of this insect was to delay seeding wheat until after May 15. The resulting crop escaped infestation because of the retarded plant during the period of the sawfly flight.

The species of Rhaphium Mg. (s.l.) may be divided, for convenience, into two group—those with white-faced males and those with black-faced males. Since the North American species of the genus were last revised (Curran, 1926, 1927), 13 species belonging to the former group have been described. In this paper one species with black-faced males is described as new, one is recorded from the Nearctic region and one from Canada for the first rime, and one species with white-faced males is also recorded from Canada for the first time.

The program of biological studies and experiments in chemical control of mosquitoes at Churchill, Manitoba, in 1947 and 1948 (Twinn et al., 1948; Twinn, 1950) was extended in 1949 to include Goose Bay, Lahrador. The program at Goose Bay was primarily designed to develop control measures for the northern species of biting flies. since the control experiments were scheduled for definite periods during the summer in 1949 (Twinn et al., 1950), limited biological studies were carried on as circumstances permitted. These field studies produced information on the species of mosquitoes present and their development and ecology. Data obtained in 1949 from field observations, collections, identifications of adult and immature forms. and limited laboratory rearings are summarized in this paper. Additional data obtained by officers of the Division of Entomology in 1950 under similar circumstances have been included, in some cases as confirmation of observations in 1949.

Only two species of Corixidae, commonly known as water boatmen, are known to occur in both the Old and New Worlds. One of these is Callicorixa producta Reuter, which Hungerford (1948) has divided into three subspecies. On the basis of existing records the typical subspecies is restricted to the Scandinavian peninsula and Finland. The second subspecies, producta sackalinensis (Matsumura), is so far known only from northern Manchuria and Sakhalin Island. The third subspecies, producta noorvikensis Hungerford, appears to straddle the Rering Sea, specimens being recorded from near Kolyma River in Siberia and from Bering Island in the Komandorskies east across Alaska and Northwest Territories to Hudson Bay.