pts=Tuples[Range[-2.5,2.5,0.5],2];

StreamPlot[{Cos[x+y^3],Sin[y+x^3]},{x,-3,3},{y,-3,3},StreamPoints->{pts->Thick,Automatic,{Forward,Scaled[0.25]}},Epilog->{PointSize[0.015],Black,Point[pts]},StreamScale->None,StreamColorFunction->"Rainbow"]