Nepedia
Back to Discover
Advanced Reader
🧬

Sawfly

life science Maturity 7-9 Next article →

Sawflies are a diverse group of insects within the suborder Symphyta. They belong to the larger order Hymenoptera, which includes bees, ants, and wasps.

Sawfly (Nematus septentrionalis) larvae
Sawfly (Nematus septentrionalis) larvae

While they are often confused with wasps, sawflies have several distinct physical and biological differences. The name "sawfly" comes from the female's ovipositor, which is an organ used to lay eggs. This organ has a serrated, saw-like appearance. Females use it to cut slits into plant tissue to deposit their eggs.

Dolerus nitens
Dolerus nitens

This process ensures the eggs are protected within stems or leaves.

The most significant physical difference between sawflies and other Hymenoptera is the body shape. Most wasps, bees, and ants belong to a group called Apocrita. These insects possess a narrow "wasp waist" known as a petiole. Sawflies lack this constriction. Instead, the segments connecting the abdomen to the thorax transition smoothly. This anatomical feature is why their scientific name, Symphyta, means "grown together" in Greek.

Entomologie1
Entomologie1

Because of this, sawflies are considered a more primitive or basal group within the order.

Sawflies undergo a complete metamorphosis consisting of four life stages: egg, larva, pupa, and adult. The life cycle begins when a female uses her ovipositor to lay eggs in rafts or pods. Once the eggs hatch, the larvae emerge. Many sawfly larvae are herbivorous and look very similar to caterpillars. However, you can tell them apart by looking at their legs. Sawfly larvae have a different number of prolegs and lack the tiny hooks, called crochets, found on caterpillars.

Yellow Flag Iris Sawfly (Rhadinoceraea micans) showing damage to plant
Yellow Flag Iris Sawfly (Rhadinoceraea micans) showing damage to plant

As the larvae reach maturity, they seek protection in soil or bark to pupate. The adult stage is quite brief, often lasting only 7 to 9 days.

The history of sawflies reaches far back into the Triassic period. Fossil evidence shows they first appeared approximately 250 million years ago. The family Xyelidae includes some of the oldest known Hymenoptera fossils. One specific fossil, Archexyela ipswichensis from Queensland, is between 205.6 and 221.5 million years old.

Xyelapusilla
Xyelapusilla

In the 1800s, zoologist Carl Gerstaecker helped organize our understanding of these insects. In 1867, he established the name Symphyta. He distinguished them from the Apocrita by noting that sawflies have nine dorsal half segments, while Apocrita have only eight. This was due to the transfer of the first abdominal segment to the thorax in the latter group.

There are approximately 8,000 described species of sawflies across more than 800 genera. They are found globally, though they show much higher diversity in the northernmost hemispheres. The Tenthredinoidea is the largest superfamily, containing about 7,000 species. Within this group, the family Tenthredinidae is the most massive, with roughly 5,500 species.

Diprionpini
Diprionpini

Sawflies vary greatly in size. While many are small, the species Urocerus gigas can reach lengths of 50 millimeters. The largest known prehistoric sawfly, Hoplitolyda duolunica, had a massive wingspan of 120 millimeters.

Sawflies occupy different ecological roles depending on their species. The vast majority are herbivorous, feeding on plant matter. However, the superfamily Orussoidea consists of parasitoids. These are insects whose larvae live on or inside other hosts. Specifically, Orussoidea larvae are carnivorous and eat the eggs or larvae of other insects.

Orussus coronatus
Orussus coronatus

Some sawflies also use mimicry for survival. They may act as Batesian mimics, meaning they evolve to look like stinging wasps or bees to scare off predators. This can lead people to mistake their ovipositor for a stinger.

Because of their feeding habits, sawflies can impact human activities. Large populations of the pine sawfly can cause significant damage to economic forestry. Other species, like the iris sawfly, are major pests in horticulture. Outbreaks can lead to defoliation, which causes stunting or even the death of trees.

Diprionpini
Diprionpini

To manage these insects, people use insecticides, mechanical methods, or natural predators. In nature, sawflies face many threats from birds, shrews, and other insects. Some larvae have even evolved to regurgitate irritating liquids or cluster together to improve their chances of survival.

Forde Caterpillars 2012
Forde Caterpillars 2012
647 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (18)
File:Sawfly (Nematus septentrionalis) larvae.jpg
Sawfly (Nematus septentrionalis) larvae.jpg
File:Dolerus nitens.jpg
Dolerus nitens.jpg
File:Entomologie1.jpg
Entomologie1.jpg
File:Xyelapusilla.jpg
Xyelapusilla.jpg
File:Diprionpini crop.jpg
Diprionpini crop.jpg
File:Caenolyda reticulata (cropped).jpg
Caenolyda reticulata (cropped).jpg
File:Hartigia linearis.jpg
Hartigia linearis.jpg
File:Hymenoptera Vielfalt Horntail.jpg
Hymenoptera Vielfalt Horntail.jpg
File:Xiphydria prolongata crop.jpg
Xiphydria prolongata crop.jpg
File:Orussus coronatus.jpg
Orussus coronatus.jpg
File:Specimen of Podalonia tydei (Le Guillou, 1841).jpg
Specimen of Podalonia tydei (Le Guillou, 1841).jpg
File:Syntexis libocedrii.jpg
Syntexis libocedrii.jpg

+ 6 more

More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.