Math 450, September 6, 2002 (R. B. Kearfott) -- The predator-prey example on page 504 of Boyce and DiPrima, seventh edition.

\(\(
f[x_, y_] = \ {x*\((1 - 0.5  y)\), y*\((\(-0.75\) + 0.25*x)\)}\)\)

<< Graphics`PlotField`

PlotVectorField[{f[x, y][[1]], f[x, y][[2]]}, {x, 0, 
        10},  {y, 0, 10},  Axes  -> True, ScaleFunction -> (1&),  
      AspectRatio  ->  1]