Hymemopterans (Class Insecta, Order Hymenoptera) have two pairs of wings, chewing mouthparts, well developed compound eyes and most females have an ovipositor, which may be modified into a sting. Hymenopterans are fourth in species richness on the planet, behind beetles, flies, and lepidopterans (butterflies and moths).

There are 12 species of ants, 110 species of bees, 111 species of sawflies,and 24 species of vespid wasps confirmed present in the NWT. Of these, two species of bees and five species of sawflies are alien. An additional four species of ants and three species of bees are expected to occur in the NWT.

Bees

As the major group of animal pollinators, bees (Superfamily Apoidea) are considered keystone organisms in most terrestrial ecosystems, including highly modified agroecosystems, as they facilitate plant reproduction. Canada is home to over 900 bee species, with most species found in the southern part of the country. However, many bee species extend into northern parts of the country. The most familiar group in the North, the bumble bees (Bombus spp.) are very common and conspicuous members of the NWT bee fauna.

The diversity of bees is not restricted to the number of species, as bees also vary considerably in their biology. Most bee species are solitary. Each female works alone to collect pollen and nectar to provision her nest, and once she lays each egg, there is no further contact between mother and offspring. Solitary bees are usually only active as adults for a short period of time, perhaps 3 to 6 weeks, the timing often corresponding to the bloom period of their preferred plants. Some species have specialized relationships with a narrow range of host plants, such as willow (Salix spp.). Other solitary bees are pollen generalists that visit flowers of a wide range of plant species.

In contrast, some bees, including most bumble bees and many sweat bees (Family Halictidae) are social for part of their life cycle – although they all start each year as a mated solitary female (potential queen) as the summer progresses workers are produced, after which time the queen becomes a full-time egg layer. Bumble bee colonies are thus active from the early spring until the autumn, and colony growth depends on floral resources being available throughout the season.

Another group of bees are called cuckoo bees. Female cuckoo bees sneak into the nests of other bees and lay their eggs on the food provisions collected by the host species. Thus, these bees do not collect pollen themselves and must rely on the stores of their host species.

At present, not much is known about the status of most of the NWT’s bees, largely because sampling events are relatively rare compared to most parts of the country, and much of the territory has not been sampled at all.

Four bumble bee species occurring in the NWT have been assessed as at risk in Canada. The conservation of Canada’s pollinators is a vital concern. At present it appears that the bee fauna of the NWT is facing less severe threats than in southern Canada – habitat loss, pesticide use, and for bumble bees, increased pressure from pathogens. Though the western bumble bee and yellow-banded bumble bee populations in the North may have relatively high pathogen loads, the additive pressures of land use practices seen in the southern parts of the country seem to be absent for most of the NWT.

Interest in bees has increased in the NWT over the past five years. We have seen more inventories by enthusiastic insect collectors.

Ants

Ants (Superfamily Formicoidea) have two characteristic body features that distinguish them from other hymenopterans. First, although like most hymenopterans, the waist of an ant is constricted between the thorax (middle body part) and the abdomen (tail), in ants this constriction has one or two distinct bulbous nodes (bumps) at the waist constriction. Second, ants have distinctively bent or elbowed antennae.

Ants are highly social with different castes or forms within their social organization (i.e., the queen, workers or sterile females, and males), and they live in colonies forming a nest that remains in that fixed location for many years. Most of the ant specimens encountered in any location are the wingless female workers, which are far more numerous and active than the other castes (i.e., males, and the newly emerged winged female queens that later lose their wings).

The actual number of ant species in Canada is not known, although at present there are about two hundred species recorded. Most of these are within the southern parts of the country. The ant fauna of the NWT includes six genera, but the distribution of these species throughout the territory is poorly documented, and there are likely additional species to be recorded. Some of the more common ants include the boreal carpenter ant (Camponotus herculeanus). At present this species is the only carpenter ant recorded from the NWT. The species ranges throughout the boreal forests and nests within cavities it excavates from rotten logs, stumps, or from under stones or in old housing timbers. They are also known to tend to aphid colonies living on plants, harvesting and feeding on the aphid’s honeydew, and protecting them from predators. This circumpolar species can survive temperatures below -40° C and is considered the most cold-tolerant ant known.

The Myrmica ants are distinguished by the long spines on the back of the thorax (middle body part), and range widely throughout the boreal forest, nesting mainly in soil, under rocks, moss mounds and sometimes under lichens.

The most noticeable ant nests encountered in the NWT are created by some of the Formica ants. For example, the podzol mount ant (Formica podzolica) nests in acidic infertile podzolic soils and creates large, distinctive mounds. The New World red-bearded ant (Formica neorufibarbis) is one of North America’s most cold-hardy ant species, ranging up into the taiga.

Ants play vital roles as predators, scavengers, and dispersal agents of seeds and fungal spores in terrestrial ecosystems; they aerate and till the soil, have intricate relationships with other flora and fauna, and have been used to monitor and assess environmental change. They are ubiquitous and abundant throughout the terrestrial environments of all continents except Antarctica.

At present, there are no documented occurrences of non-native ants in the NWT, and if these are detected in the future, they will likely be within or near to homes and buildings. Most ant collections within Canadian museums are not databased and there is insufficient survey coverage for ants throughout Canada, particularly in the North, so any observation is very useful to increase our understanding of ants in the NWT.

Vespid wasps

When most people think of wasps, they think of the social yellowjackets, which make up only a handful of species, belonging to the family Vespidae. However, most vespid wasps are potter and mason wasps (subfamily Eumeninae), which are a primarily tropical group. In the NWT, only two of the five North American subfamilies of vespid wasps are represented: the yellowjackets (subfamily Vespinae) and the potter and mason wasps (subfamily Eumeninae).

Vespid wasps are aculeate (stinging) wasps. The females have a sting – a modified ovipositor (egg laying tube). The sting may be used to subdue prey, as in potter and mason wasps, or primarily as a defensive weapon, as in the yellowjackets. The sting is retracted within the end of the abdomen in these and other aculeate wasps – if you see a long, obvious ovipositor on a wasp, it is not used to sting, and these wasps are normally harmless.

The potter and mason wasps, unlike their yellowjacket cousins, live mostly solitary lives. Females build individual nests, lay an egg in a chamber, or cell, and afterward provide their offspring with food in the form of caterpillars or beetle larvae. The cells, with one egg and enough food to see the wasp larva through development, are then walled off with mud. These prey items are usually paralyzed with a sting from the mother wasp. The mother has no contact with her sons and daughters and proceeds to construct additional cells in the same nest, or another nest.

The type of nest built by these wasps varies depending on the species. In the NWT, most species use abandoned beetle burrows or other holes in wood, including nail holes or hollow pieces of plant material or even aluminum (such as a window frame or lawn chair support), to make a linear series of cells. Each of these is walled off with soil moistened with water, to produce a mortar. Several species use the same technique, carrying water, and possibly nectar, in part of the “stomachs” and flying to a site with suitable soil which they moisten to construct a separate mud nest. These nests can be unruly collections of cells, as is the case for Walden’s mason wasp, or they can be elegant, pot-like structures with fluted necks, like those made by members of the genus Eumenes represented in the NWT by one species, the cross potter wasp. These nests have garnered their makers the name “potter wasps”.

The beloved mason wasp (Odynerus dilectus) is one of two mason wasps found in the NWT so far that is known to dig a nest in soil, removing pellets moistened by water. This species also erects a small, curved turret at the nest opening. These nests may have several cells and the stored prey is unusual as well, consisting of both beetle larvae, sometimes including those of alfalfa and clover weevils, and caterpillars. Members of another group, the genus Symmorphus, which has a more northerly distribution than most mason wasps, hunt for leaf beetle larvae to stock their larder, including willow-feeding species.

Most potter and mason wasps, however, hunt solely for caterpillars, at least some of which are important pests, including spruce budworm and large aspen tortrix and other defoliators, and so play an important role as natural biological control agents.

Everyone has a story (or three) about yellowjackets, the colonial, conspicuous wasps that share our backyards and picnics. The group to which yellowjackets belong, the subfamily Vespinae, includes true hornets (the genus Vespa), and a generally more tropical group, the “paper wasps” (Polistinae), neither of which occur in NWT. One of the large yellowjackets, black and white in colour, has come to be labelled the bald-faced “hornet”, but is not actually a true hornet, despite its larger size.

Our yellowjackets build globular nests out of pulp that they make from strips of wood peeled from dead branches and logs (or untreated porch railings), chewed and mixed with water. The young are raised in paper cells that are held in flat combs suspended within the protected walls of the nest. There are two groups of yellowjackets in the NWT: species in the genus Vespula generally build their nests in cavities in the ground (e.g. rodent burrows) or in spaces in old trees or the walls of houses whereas members of the genus Dolichovespula generally build their nests above ground, suspended from tree branches or beneath the eaves of houses or cabins. The name Vespula means “little hornet” (true hornets are much larger) and Dolichovespula refers to the slightly longer face of these wasps.

Yellowjacket queens begin their new colonies on their own in the spring, and every winter if the temperature is low enough, as it is in the NWT, the entire colony dies except for the newly mated young queens. These individuals overwinter under bark, dead leaves, or in crevices, surviving punishing temperatures, protected by the insulation of snow cover and by special “anti-freeze” chemicals in their body fluids. The queens carry sufficient sperm from mating in the fall or spring; these fertilize eggs in their bodies. In May, the queen begins to build a nest of paper, which includes a small comb with perhaps a dozen cells, in each of which she lays an egg. These female larvae will develop into workers. The queen must raise them on her own – this phase is critical to the future productivity of the colony, and many nests fail due to death of the queen, often because of cool, wet weather, or attacks by other queens.

Adult yellowjackets feed almost entirely on nectar and ripe fruit, but their young are fed various solid foods, including predominantly insects and spiders, or in some species, carrion and other meat (e.g. picnic hamburgers). This food is not stung and paralyzed as it is in the solitary vespids but grasped and chewed to produce a sort of bug “pablum”. Only a few species scavenge meat; in the NWT the pesky yellowjackets around your table are likely Alaska yellowjackets (Vespula alascensis). The workers begin rapidly to enlarge the nest, excavating a larger hole in subterranean nests, and building new combs and outside paper envelopes. The first larvae raised by the queen take over all the duties outside and inside the nest, except egg-laying, and themselves raise more workers increasing the size of the colony. Eventually, in mid-summer, combs for new queens and males are built. They leave the nest in late summer and mate, and the fertilized queens search out sites to overwinter, going into torpor, a kind of resting state, often well before the colony begins to senesce. The remaining larvae die of starvation or are eaten by the workers.

There are two rather unusual yellowjackets that occur in the NWT, both of which forego the hard work of establishing their own nests but rely on the work done by other queens. These “cuckoo” or parasitic yellowjackets (Vespula infernalis and Dolichovespula arctica) invade the nests of other species of yellowjackets, and either kill or dominate the queen, lay their own eggs, and the host workers raise the “cuckoo” young as if they were their own.

The sting of a yellowjacket worker, unlike those of honey bees, is only microscopically barbed, so it can be used for repeated stings by one individual. Wasp venom contains up to six or seven main components, including histamine, serotonin, kinins,  and acetylcholine. Histamine initiates the general swelling reaction, while kinins and acetylcholine probably cause the immediate, burning pain. For most people, the pain from a wasp sting subsides quickly, and is soon forgotten, but for those with a true allergic reaction to the venom, stings can be serious. Usually, wasps are quite docile and do not sting unless the nest is threatened or a worker is unknowingly interfered with – caught in clothing or stepped on.

Although we tend to think of yellowjackets as pests to be discouraged from our back yards they, like the solitary potter and mason wasps, are actually highly beneficial. Think of the number of plant-hungry insects several hundred wasps consume each day. Unless you are threatened by a growing colony whose flight path goes by your back door or who live under your front porch, or you are allergic to their stings, it is best to leave the nestalone and let the wasps do their job.

Sawflies

Sawflies (including horntails) are a group of insects related to ants, bees, and wasps that together comprise the order Hymenoptera.

Almost all sawflies are herbivorous as larvae, when they resemble caterpillars. Most larvae are external feeders on flowering plants, but some feed on conifers or ferns and some are internal plant feeders, for example, horntail larvae (Family Siricidae) live inside wood, whereas some species in other groups feed inside stems or form leaf mines or galls.

As adults, most sawflies feed on pollen and nectar, but some are active predators of other insects. Adult sawflies resemble wasps in that they have four membranous wings and biting mouthparts, but unlike wasps like hornets and yellow jackets, sawflies do not have a narrow constriction in their body (the so-called “wasp-waist”).

Most sawflies are not of great consequence to humans, but some can be major pests such as a few species of stem sawflies (Family Cephidae) that feed inside the stems of wheat and other crops, and conifer sawflies (Family Diprionidae) that can be major forest pests. Conversely, some species that have larvae that feed on weeds are considered beneficial. There are just over 8,600 described species of sawflies in the world.

An ongoing series of recently published papers is providing a checklist of all the described species of Hymenoptera recorded in northern North America including lists for all Canadian provinces and territories. The first paper in this series (Goulet and Bennett 2021) dealt with the sawflies. The NWT species represent about 15% of the number of species known in Canada. By far the majority of the species of sawflies in the NWT belong to the family Tenthredinidae. This is the largest family of sawflies in Canada and the world.

The NWT is also home to one web-spinning sawfly (Family Pamphiliidae), a wood wasp (Family Xiphydriidae), and horntails, which get their common name because the females have a long “horn” extending from the posterior of their abdomen. There are also members of the family Argidae that are distinguished from all other sawflies by having their antenna reduced to only three segments and four species of the family Cimbicidae which can be very large (bodies up to 2 cm in length) and have antennae that are clubbed at the end. Male cimbicids can be commonly found at the top of hills where they congregate for finding and competing for mates.

Species of the family Xyelidae are all small (only 3 to 5 mm in body length) and the larvae develop within male pine cones. Xyelids are the most ancient group of Hymenoptera. Fossils have been found dating back to the Triassic, over 200 million years ago.

Our knowledge of the sawflies of the NWT is good relative to other groups of Hymenoptera. Still, it is clear that there are many unrecorded or even undescribed species of sawflies in our region. This is especially true in some groups within the family Tenthredinidae that are closely associated with willows. There is a high diversity of willows in northern Canada; it is certain that there are many new records and new species of sawflies that await discovery.