Spruce Budworm Moth Flight and Storms, Further Studies Using Aircraft and Radar

Abstract

In two further detailed case studies using special insect-detecting radars and aircraft, the height, density, speed and extent of displacement of night-flying spruce budworm months (Choristoneura fumiferana [Clem.]) were found to be substantially greater on nights of widespread and heavy precipitation than so far reported for less disturbed weather. The first of these studies showed moths at high density (10−2 m−3) and a, substantial heights (500–700 m AGL, 800–1100 m MSL) in the immediate vicinity of active cumulonimbus. The other case provided well documented observations of spruce budworm moths flying at high densities at more than 600 m above sea level, traveling for several hours in and among rainstorms with winds of about 50 km h−1; one aggregation covered some 104 km2 at densities which gave a total of the order of 1010 moths, and represented an airborne biomass of hundreds of tonnes.