Blow flies are common insects found around decaying organic matter. Understanding their appearance helps with identification and management. These flies play a role in natural decomposition. Knowing their characteristics allows for distinguishing them from other common fly species.
Distinctive Adult Features
Adult blow flies typically measure between 1/8 and 5/8 of an inch (approximately 6 to 14 millimeters), making them generally larger than common house flies. Their most striking characteristic is their metallic coloration, which can range from bright blue, green, or copper to shiny black or bronze.
The head of an adult blow fly features large, prominent compound eyes that are often reddish-brown. These eyes can be quite close together, providing a wide field of vision. They possess short antennae, which typically have a feathery appearance. Their mouthparts are designed for sponging, enabling them to absorb liquids rather than biting.
The robust body of the blow fly, particularly the thorax, often matches the metallic coloration of the rest of the body and may appear slightly hairy. Some species also have noticeable bristles on their bodies. They have a single pair of transparent or slightly tinted wings, which are typically held flat over their backs when at rest. Their abdomen is segmented and oval-shaped, continuing the overall metallic color. Blow flies are equipped with six dark, bristly legs.
Differentiating from Similar Flies
Distinguishing blow flies from other common flies relies on observing their specific visual traits. House flies, for instance, are typically smaller than blow flies, measuring around 6 to 7 millimeters in length. Unlike the metallic and often vibrant blue, green, or copper hues of blow flies, house flies exhibit a duller gray appearance with variations of gray and black. House flies also tend to have a more elongated body shape and smaller eyes compared to the rounder, larger-eyed blow flies.
Flesh flies can be similar in size to blow flies, but they lack the characteristic metallic sheen. Instead, flesh flies are typically gray with three dark stripes on their thorax and a distinct checkered pattern on their abdomen. Their body shape is often more streamlined with a tapered abdomen, contrasting with the fatter, more rounded appearance of blow flies.
Fruit flies are considerably smaller than blow flies, usually measuring only about 1/8 of an inch long. They often have reddish eyes and their bodies are typically brown or yellow, without any metallic coloration.
Larval Stage Appearance
The larval stage of blow flies, commonly known as maggots, possesses distinct visual characteristics. These larvae are typically creamy white or yellowish in color. They have a cylindrical body shape that tapers towards the head end, giving them a pointed appearance at one end and a broader, rounder appearance at the other.
Blow fly maggots are legless and segmented, appearing soft and resembling small worms or grains of rice. They are equipped with hook-like mouthparts, which they use for feeding. Mature maggots can reach lengths ranging from approximately 9 to 22 millimeters (0.4 to 0.8 inches) depending on the species.