In addition to looking terrible, bug residue will harm your paint & clear coat. Certain bugs, such as Love Bugs, Cicadas, etc., secrete an acid when they are smashed on your vehicle that bonds to the paint.  Even bird droppings are acidic.  The longer they remain on the paint the harder they become to remove, especially if your vehicle is in the sun.  You need to get them off as soon as possible (meaning quickly) or they may permanently discolor the paint!