Information from University of Minnesota Extension

Soybean aphids increase at such a rapid rate that the females are essentially cloning themselves. The University of Minnesota Extension Web site explains that females give birth to live young nymphs at a rate of three to five per day. The female nymphs then mature in five to seven days and then begin producing their own young.

This speedy life cycle stresses the importance of scouting early and often because in an experiment when temperatures ranged from the mid 70s to early 80s – ideal conditions for aphids – populations doubled in as little as two days.

A 2001 study held in Houston, Minn., demonstrated the dynamics of soybean aphid populations. The field was colonized with soybean aphids when the plants reached the V1 to V2 stage (first and second trifoliate). Within four weeks, the entire field had been colonized and the populations increased dramatically. Just one week later, the densities reached five times the injury level at 5,000 per plant.

For more information on this population growth study from the University of Minnesota, click here.