The number of mosquitoes $M(x)$, in millions, in a certain area depends on the June rainfall, $x$, in inches, according to the equation $M(x)=2 x-x^{2}$. What rainfall produces the maximum number of mosquitoes?

Step 1 ：The problem is asking for the maximum value of the function \(M(x)=2x-x^2\). This is a quadratic function, and the maximum value of a quadratic function occurs at its vertex.

Step 2 ：The x-coordinate of the vertex of a quadratic function given in the form \(f(x)=ax^2+bx+c\) is \(-b/2a\). In this case, \(a=-1\) and \(b=2\), so the x-coordinate of the vertex is \(-2/(-2)=1\).

Step 3 ：Therefore, the rainfall that produces the maximum number of mosquitoes is 1 inch.

Step 4 ：Final Answer: The rainfall that produces the maximum number of mosquitoes is \(\boxed{1}\) inch.