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AbstractPupae of the onion maggot, Hylemya antiqua(Meigen), did not complete their development when irradiated with 3.0 kiloroentgens within five days of pupal formation. Older pupae were not adversely affected. Females from treated pupae were sterile and laid no eggs when caged with normal males. The males from treated pupae were sterilized to a high degree, yet normal females mated with them and laid normal complements of eggs. Less than 0.2% of 10,616 eggs laid by normal females caged with sterile males hatched. A 6:1 ratio of sterile to normal flies reduced egg hatch to 1.7%.

The seed-corn maggot, Hylemya cilicrura(Rond.), infests a wide range of hosts in all provinces of Canada and is also a pest in the Yukon and the Northwest Territories. H. liturata(Meig.) frequently occurs in smaller numbers along with H. cilicrura. H. lituratahas not ,been recorded from Alberta, Saskatchewan, and Manitoba (Brooks, 1951). Detailed accounts of the species have not been published by Canadian entomologists, though H. cilicrurahas been known as a pest of cultivated crops in Canada for over 70 years. In southwestern Ontario the seed-corn maggot is one of the most serious soil pests of vegetables and field crops.

AbstractA method for continuous rearing of the carrot rust fly, Psila rosae(Fabricius), has been developed for the first time. All stages of the rearing were conducted in a temperature cabinet maintained at 64 ± 2°F. Adults in a screen cage were fed water, honey, soybean flour and yeast. The females oviposited in the soil of potted carrots. Eggs were periodically removed with the top layer of soil to gallon jars containing several carrots layered in muck soil.Field collected puparia emerged satisfactorily at 70°F., but not at higher temperatures. In the laboratory population there was a preponderance of males. A generation of carrot rust flies was completed in approximately 80 days.

AbstractParathion was the most effective ovicide for European corn borer eggs. Six other materials gave at least 50% mortality at 100?p.p.m., but 17 had little or no activity. Corn borer larvae were more susceptible to insecticides, and probit-mortality data was determined for 17 materials.In 1970 and 1971 heavy populations of borer were controlled on sweet corn and peppers by twice-weekly sprays of carbaryl, Lannate, and Phosvel. Furadan applied weekly provided good control, and several of the experimental compounds were effective.

AbstractOviposition of the predacious mites Phytoseiulus persimilisand Typhlodromus fallacisbegan 2 days after mating, reached a peak in 1 week, and then declined irregularly. The rates of oviposition were higher, and the oviposition period shorter at 26° than at 20°C. P. persimilislaid 47% more eggs than T. fallacis. The generation time for both species was very dependent on temperature. Minimum values of 112 hours for P. persimilisand 127 hours for T. fallaciswere obtained at 28°.Calculations of potential predator populations from the generation time, age-specific fecundity, and proportion of females were made on a daily basis for successive generations. The potential number of living females derived from one mated pair increased logarithmically after a few cycles representing new generations. The rate of increase of P. persimilispopulations was 26% higher than that of T. fallacis, and in both species the rate at 26° was about double the rate at 20°.

AbstractLaboratory studies were conducted with the carrot rust fly, Psila rosae(Fabricius), to determine the effect of irradiation on reproduction. Irradiation of 15-day-old pupae with 1.4, 2.8 and 4.3 kiloroentgens did not adversely affect emergence. Treated females caged with normal males laid a few sterile eggs when the treatment was 1.4 kr. but none at the higher doses. Normal females caged with treated males laid a normal complement of eggs, and the per cent hatch was 10, 2 and 0 with treatments of 1.4, 2.8 and 4.3 kr., respectively. When flies of both sexes from pupae treated at 3.0 kr. were mixed with normal flies in a ratio of 6:1, the number of larvae were reduced by 93%.

The seed-corn maggot, Hylemya cilicrura(Rond.), is a cosmopolitan pest and feeds on a wide range of hosts. The maggots cause extensive damage to seeds and seedlings of beans, soybeans, peas, corn, and cucurbits. Hitherto laboratory investigations have been hampered because the maggot has been very difficult to rear continuously.Biological studies have indicated that such diverse diets as soybeans (Harukawa et al., 1934), cottonseed meal and fish meal (Reid, 1940), and potato (Leach, 1926) serve to rear the maggot to the adult stage. However, it has been difficult to maintain an adult colony for the time required for mating and oviposition. Reid (1940) used field-collected flies as a source of eggs in his experiments, but failed to get a second generation. Successive generations were reared by Ristich (1950), who provided a high protein diet for adults held in glass cages; in attempts to follow this method at Chatham, only one complete generation could be reared. A more satisfactory method of rearing the species continuously is described in this paper.

During studies on the control of the onion maggot, Hylemya antiqua(Meig.), in late September, 1958, from one to 10 dead adults were found clinging to the tops of onion leaves in a three-acre field of green bunching onions in the Toronto area (Fig. 1). The dead flies were more abundant in the outside three rows, adjoining a non-cultivated grassy area, than throughout the rest of the field. A fungal growth was evident between the abdominal terga and sterna in many specimens. Infected live flies were somewhat pale, appeared bloated, and moved very sluggishly in comparison with non-infected adults. Dead flies were sent to Dr. G. Bucher, Entomology Laboratory, Belleville, Ontario, who identified the pathogen as Empusa muscaeCohn.