Lacewings and their relatives are insects in the Order Neuroptera (Latin for “net-winged insects”). Neuroptera are a relatively small insect order, mostly found in the tropics. The NWT is home to at least three families: green lacewings (Family Chrysopidae), brown lacewings (Family Hemerobiidae), and spongillaflies (Family Sisyridae). Recent unverified collections indicate that members of another family, the dustywings (Family Coniopterygidae), are also present in the NWT.

Adult Neuroptera typically have narrow, cylindrical bodies, long antennae, and long wings held tent-like over the body when at rest. Front and hind wings are similar in size and shape and both have a net-like pattern of veins. The wings resemble those of dragonflies but, unlike those masters of flight, lacewings are generally weak fliers. They are similar to dragonflies in being voracious predators of other insects both as larvae and adults. Some species are important predators of agricultural and forest pests like aphids. Both green and brown lacewings are attracted to lights and often find their way into homes on summer nights.

Typically, lacewing eggs are laid in spring on plants harbouring suitable prey like aphids. The eggs are laid in clusters with each egg suspended above the leaf surface at the end of a long stalk. This isolates the egg from the leaf and nearby eggs thus avoiding predation by its siblings and other insects, like lady beetles, also commonly found feeding on aphids. The young lacewing larvae, often called aphid lions, are equipped with a pair of sickle-shaped mouth parts they use to pierce and inject digestive enzymes into small insects. Then they reverse the flow and imbibe the body fluids and dissolved organs. Some species cover themselves with pieces of debris creating a cloak, which acts as both camouflage and a protective shell. To grow, a lacewing larva must periodically shed its exoskeleton. Once it attains full size the larva spins a small, silken cocoon in which to pupate. After a few days to several weeks, it emerges as a winged adult. Adult lacewings range in size from about 6 to 20 mm. The development time from egg to adult varies from a few weeks or months to a year or more depending on the species, abundance of food and temperature. When the adult emerges it will mate and, if early enough in the summer, a female may lay eggs and produce a second generation. The adult lacewing will continue to feed on other insects, pollen, and other food sources into fall then seek out a suitable hiding place to spend the winter months.

Green lacewings have very sensitive hearing organs, called tympana, located at the base of the front wings. These tympana are used both to sense the low-frequency mating calls of nearby mates and to detect the ultrasonic calls of bats to avoid predation. These organs might also aid in sensing and locating prey species feeding on plants.

Spongillaflies are so named because the aquatic larva uses its threadlike mouthparts to pierce and ingest the contents of freshwater sponges and bryozoans (moss animals). The larva breathes through gills on the abdomen. When full grown, the larva leaves the water to spin a cocoon in a protected spot then pupates and emerges the next year as an adult that closely resembles a brown lacewing. After mating, the female will lay eggs on leaves overhanging the water. This allows her young to drop in and immediately begin foraging for sponges.

Like most insect groups, the Neuroptera have been collected sporadically from relatively few locations in Canada and are not well represented in museums. What we currently know about Neuroptera in the NWT is based on a recent survey of the literature and specimens held in museums. This survey found approximately 120 specimens from 25 collections from 1922 to 2013 (contrast this number to the 2,900 birds observed during the Yellowknife Christmas Bird Count in 2013). An additional 154 specimens have been collected from 2014 to 2020 though at present only six have been identified to species level. Identification of the remaining specimens is likely to add at least one additional species record and a number of distribution records.

Most of these specimens have been collected near Great Slave Lake, Fort Smith, Great Bear Lake, and the Mackenzie River valley and delta region near Inuvik and at Tuktoyaktuk, and along the Dempster Highway. The most northerly species record is the lined brown lacewing (Wesmaelius nervosus) from Victoria Island. This indicates that some species can be found throughout the territory south of the Arctic Circle and in favourable habitats north of it.

A more intensive and distributed sampling effort should increase the number of species known to occur in the NWT. The forested and topographically diverse region in extreme southwest near Fort Liard and at lower elevations in the Nahanni National Park Reserve are likely to have the highest Neuroptera species richness. Moving northward and eastward from here the likelihood of finding new records or higher diversity diminishes but this does not mean these areas should be neglected. Since the 2015, two species of brown lacewings have been newly recorded near Great Slave Lake. We know virtually nothing about the distribution of species across the vast expanse of the NWT, so any collections provide valuable information about the biodiversity our area. Establishing baseline distributions of species now is critical if we are to assess the effects of changing climate on the fauna of the NWT.

There are 16 species of lacewings confirmed present in the NWT, including the common green lacewings included in the list below as a single species complex. This taxon needs additional investigations to determine which other additional species are present in the NWT. Eight more species are expected to be present in the NWT.