Pollen Beetle Flight Days
Pollen beetles Meligethes spp. occur in high abundance at temperatures above 10°C. They overwinter in litter of forests and start to immigrate to rape fields in spring. Most damage is done, when adult beetles feed on buds. Females lay their eggs into buds, but once the flower occurs no damage is done by larval feeding on pollen. There are a lot of reports, which describe the resistance of the pollen beetle against special insecticides. Color: Metalic green, blue, violett, bronce or black.
Size: 1,5 - 2,7 mm
Habitat: Fields, Pastures, Gardens
Cycle: Femals are laying eggs into the buds of the rape seed plant. Therefore they have to bit trough petal and sepal leafs. Eggs are deposited on anther and stigma. The hatched larvae feed at the already opened flower (no damage) and the last larval stage leaves the flower and goes to the soil, where it pupate for about one week. First generation of beetles are hatching during sommer. They still feed on different flowers (mostly attrackted from yellow) and at the end of summer they start to fly to refuges to hibernate. Pollen beetle has one generation per year.
Feeding: Pollen of many varieties with preferation for cruciferes.
Flight Period: Pollen beetle start flying if the soil temperature is higher than 9°C and the air temperature about 15°C and low relative humidity. Flight of Pollen beetle lasts about four weeks (in Austria between begin to mid of April til mid of May). In FieldClimate.com we just determine the occurrence of the flight by "Yes" or "NO"- so if the immigration to the field was already determined by soil and air temperatures it will stay at "YES" for the saison and the farmer has to check the occurrence on the field at that time.