Sawflies are insects that can often be mistaken for flies or wasps due to their general appearance. This article describes the appearance of sawflies, detailing key characteristics of both their adult and larval stages, to provide a clear guide for recognizing these common insects.
Key Characteristics of Adult Sawflies
Adult sawflies generally exhibit a stout, cylindrical body shape. They typically range in size from 2.5 millimeters to 20 millimeters, though some larger species can reach up to 55 millimeters in length. Their coloration is quite varied across species, frequently appearing dark like black, but also presenting in combinations of black and yellow, black and red, or even metallic blue hues. Some species mimic the appearance of wasps or bees, which can help deter predators.
A primary feature distinguishing adult sawflies from other Hymenoptera, such as wasps and bees, is the absence of a constricted “waist” or petiole between their thorax and abdomen. Despite their resemblance to wasps, adult sawflies do not possess a stinger and are harmless to humans.
Closer Look at Adult Sawfly Body Parts
The head of an adult sawfly can vary in size, shape, and sturdiness, typically featuring prominent compound eyes and three simple ocelli. Their antennae display a wide range of forms, serving as an important identification feature for different groups. These can include thread-like (filiform), club-shaped (clavate), saw-edged (serrate), or comb-like (pectinate) structures, with some male sawflies exhibiting feathery antennae.
Adult sawflies possess two pairs of membranous wings. These wings are generally clear or slightly tinted, and the fore and hind wings are typically linked together by small hooks. The pattern of veins within the wings, known as venation, is specific to different species and can aid in identification. Sawfly legs are structured for walking and clinging, featuring three pairs of true legs with spurs on their tibiae. The female sawfly’s name originates from a specialized saw-like egg-laying organ, the ovipositor, used to cut slits into plant tissues where eggs are deposited.
What Sawfly Larvae Look Like
Sawfly larvae are frequently encountered and bear a strong resemblance to caterpillars. A key distinction lies in the number and structure of their fleshy abdominal prolegs. Sawfly larvae typically have six or more pairs of these prolegs along their abdomen, while caterpillars usually have five pairs or fewer. Furthermore, sawfly prolegs lack the tiny gripping hooks that are characteristic of caterpillar prolegs.
The head of a sawfly larva is typically distinct and rounded, often appearing shiny black or reddish. Unlike caterpillars, which usually have multiple small eyes on each side of the head, sawfly larvae generally possess only a single eye on each side. Their bodies are generally cylindrical and can be smooth, hairless, wrinkled, or even spiny, depending on the species. Larval coloration is highly variable, ranging from green, brown, or black to yellowish-white, often adorned with stripes or spots. Some species have a slug-like appearance, appearing slimy or translucent. Sawfly larvae commonly feed exposed on plant leaves, sometimes clustering in groups.