The net force acting on an insect falling downward at constant velocity is

The net force acting on an insect falling downward at constant velocity is zero.

Explanation:

The net force acting on an insect falling downward at constant velocity is zero because an object is moving with constant velocity, acceleration of that object is zero because acceleration is the time rate of change of velocity. As there is no change in velocity, there is no acceleration.

According to Newton second law of motion, an object of mass m accelerate only when a net force acting on it.

                          F = ma

As there is no acceleration, there is no net force acting on it. So net force is zero.  

                          F = m(0)

                          F = 0

i think its

conduction, convection, radiation