Immature tree crickets have various patterns on their abdomen.  Some have white, some yellow.  Some have dashes, or lines, or spots.  Some are rich green, some pale green, some whitish. 

Black-horned:  white dashes

...and often have a dark area down the center.

Forbes' have thick yellowish areas along the outer edges of the dorsal abdomen.

Forbes':  Yellow thick strokes with very few spots.

This female Forbes' has a few more spots along with the yellowish lines along the side.

This young 4-spotted has a very distinct pattern.  Note the whitish lines running down the sides, the darker strip down the middle, and the whitish edge to the dark strip.

This female 4-spotted still has hints of a darker area down the center bordered by white lines.

This Fast-calling female has neither lines or spots, but rather dashes.

Davis':  Thick yellowish circles

Narrow-winged:  Thick white loops and spots

Snowy:  White spots and dashes

Western:  Wide dark line down center with slightly lighter bordering lines