Libellula quadrimaculata L. is a holarctic dragonfly which exhibits gregaricus and migratory behavior. “Immense swarms of this species have been recorded in different parts of Europe cn many occasions” (Tillyard) but such flights have not often been recorded in North America. On June 26 a large flight was observed by R. D. Bird at Brandon, Manitoba in a residential district at the south end of town. The location is thickly planted with Manitoba maple trees which reach a height of thirty to thirty-five feet. To the west and south are severa1 sloughs where the dragonflies might have bred but none of them are within a mile and most of them considerably farther. The day was hot and sultry with a maximum temperature of 85°. A violent thunder storm accompanied by hail passed just to the south in the evening. There was a light west breeze. The flight was first semen at 6.00 p.m.