The ornamental design for an insecttrap, as shown and described.
1. Insect trap
1.1 : Front
1.2 : Back
1.3 : Left
1.4 : Right
1.5 : Top
1.6 : Bottom
1.7 : Perspective
1.1 is a front elevation view of an insect trap showing our new design; 1.2 is a rear elevation view thereof; 1.3 is a left side elevation view thereof; 1.4 is a right side elevation view thereof; 1.5 is a top plan view thereof; 1.6 is a bottom plan view thereof; and 1.7 is a perspective view thereof.