Many flies also have a calypter or membranous lobe at the base the wings. They have large compound eyes and the mouthparts are adapted for sucking, piercing or sponging. The larvae, called maggots, are legless and wormlike . Mayflies Mayflies are small to medium sized, elongate, and very soft-bodied. The abdomen is long and slender with two to three long threadlike tails.
Adults have two pairs of membranous wings with numerous veins.
The front wings are usually large and triangular and the hind wings are small and rounded. Some species have hind wings that are very small or absent. The wings are held together above body when at rest. The antennae are small, bristlelike, and inconspicuous. The front legs of males are longer than the other legs, sometimes as long or longer than the body.