Insect blood, which is called hemolymph, contains various nutrients, hormones, and other things, but does not have any red blood cells or hemoglobin. That is why it is not red in color, and instead is clear or tinged with yellow or green. – Tiny Fox Lab Facts
The red color that you see upon squashing a housefly or fruit fly is actually pigment from the animal’s eyes.
Preview photo credit: Britannica