I agree. Insects are everywhere... literally. U just need to keep your eyes peeled.
Try the reservoir parks or any town garden parks that aren't too ermm... man-made.
For me, I personally like to go to more "natural" places... MacRitchie Reservoir's trails are nice... so are Lower Peirce ones... and I usually like to take some time to sink into nature... like, be absorbed into nature. That way, I'm more sensitive to tiny sounds and movements. And walk slow... =)
A good place will be the lower pierce reservoir at the boardwalk areas. For faster access, can park at the Casurina (not sure of spelling) roti plata area, where there are coupon parking, and can walk straight to the boardwalk.