Holarctic Alderflies

Sialis

Holarctic Alderflies are fascinating insects that love to live near water. They have long wings and are often seen flying around ponds and streams, where they lay their eggs.

Habitat: Wetlands

Appearance

The Holarctic Alderflies has a robust, dark brown to black body and large, smoky-grey wings with many visible veins, resembling fine lace. Its head is broad with short, segmented antennae, distinguishing it from longer-antennaed caddisflies.

KingdomAnimaliaPhylumArthropodaClassInsectaOrderMegalopteraFamilySialidaeGenusSialis

Holarctic Alderflies

Interesting facts

Adult alderflies almost never eat; they live off stored energy from their youth!

Larval alderflies can live in ponds or rivers for up to two years before transforming!

Their transparent wings, though beautiful, are not meant for long-distance travel!

When disturbed, larval alderflies wiggle rapidly to escape danger in the water!

Special abilities

Holarctic Alderflies larvae can breathe underwater using special abdominal gill filaments that help them thrive in aquatic environments.

Holarctic Alderflies adults live only a few days, dedicating their short time entirely to reproduction and laying eggs.

Holarctic Alderflies larvae have strong jaws and often hide in streambeds, ambushing small aquatic invertebrates that swim by.

Measurements & details

Wingspan: 20-40 mm
Size: 10-20 mm
Lifespan: 3-7 days
Flight Speed: 1-5 km/h
Leg Count: 6

Diet & Feeding

Alderfly larvae are fierce underwater predators, while adults usually don't eat much at all!

Age differences: Larvae are active predators, but adults typically consume only water or do not feed, focusing on reproduction.

Primary Foods

aquatic insect larvae
small crustaceans
worms
midge larvae
mayfly nymphs

Foraging Method

Ambush

Ecological connections

eaten by

Brown Trout

Salmo trutta

Larval alderflies are a vital food source for many fish species.

eaten by

White Wagtail

Motacilla alba

Adult alderflies are prey for various insectivorous birds near water.

hunts

Common Midge

Chironomus plumosus

Alderfly larvae actively prey on smaller midge larvae in freshwater.

hunts

Freshwater Shrimp

Gammarus pulex

Alderfly larvae consume various small aquatic invertebrates like scuds.

Traits

Solitary

Solitary animals live alone for most of their lives, only interacting with others for mating or parental care.

Omnivorous

This trait identifies organisms whose diet includes both plant and animal matter.

Colorful

Colorful describes organisms or objects displaying a wide range of bright and distinct colors.

Wetland

This habitat trait identifies species found in wetlands, which are areas of land saturated with water, either permanently or seasonally, including marshes, swamps, and bogs.