Insects in an Urban Garden - Hymenoptera
Ottawa Canada

In the Hymenoptera, fertilized eggs produce females, unfertilized eggs males. Sisters share 3/4 of their genes, but mother and daughter share only 1/2. A female gains more survival advantage by protecting sisters than her own offspring. That leads to an intensity of social behaviour that is almost unique to the order, being equaled outside it only by termites. Despite that genetic predisposition, however, most of our Hymenoptera species are solitary ground nesters. mouseover thumbnails for full images
There is a popular misconception that bees, honey bees (Apis mellifera) in particular, are the primary pollinators of flowering plants. I have well over 100 different flowering plants in my gardens, and (so far) 14 species of bees have visited. I'm not aware of a single plant that's pollinated only by bees. At least half are visited solely by wasps and/or flies.
Agapostemon texanus: These bees are attracted to the salt in human sweat, hence referred to as sweat bees. This is one of the most common metallic greens here. Length 10 mm. Agapostemon texanus female
Agapostemon virescens: A communal sweat bee, many females share a single nest entrance although each maintains individual areas within it. Length 9 mm. Agapostemon virescens male
Andrena dunningi: This bee is rare here, but its large size and hairless black abdomen stand out. It's eusocial, forming large colonies of individual burrows. Length 13 mm. female Andrena dunningi
Andrena rugosa: These bees usually collect pollen as food and often fail to pollinate the flower. They are my commonest bee and the earliest. Length 9 mm. female Andrena rugosa
Apis mellifera: Honey Bees were brought from Europe in the 1600's, later from other locations in Asia and Africa. Besides producing honey, hives are transported to pollinate field and orchard crops, then moved out before pesticide spraying resumes. This one may have come from a backyard apiary, if so it must be a fair distance away as they aren't common here. Length 12 mm. Apis mellifera worker
Bombus impatiens: Eastern Bumble Bees nest eusocially in several places in my garden, an advantage of zero tillage. They can always be found collecting nectar from Clematis tangutica when it's in bloom. They are more efficient pollinators than Apis mellifera as the vibration caused by their powerful wings dislodges more pollen. Only queens survive winters. Worker length 10-15 mm. Bombus impatiens
Bombus ternarius: Tricolored Bumble Bees are rarely seen in my garden, presumably the resident B.impatiens discourage them from staying. Length 12 mm. Bombus ternarius
Colletes inaequalis: A ground nesting bee, it builds cells in underground nests that are lined with a polyester secretion to preserve moisture during summer aestivation. Length 15 mm. Colletes inaequalis female
Halictus rubicundus: A solitary bee here, nesting in the ground; it's social in warmer climates. Length 11 mm. female Halictus rubicundus
Lasioglossum ellisiae: This bee is an important native pollinator. Length 4.5 mm. Lasioglossum ellisiae female
Lasioglossum fuscipenne: This is a eusocial bee - each nests in its own cell but some remain to guard the nest complex while others forage for food. Length 6 mm. Lasioglossum fuscipenne female
Nomada articulata: Cuckoo bees lay their eggs in ground-nesting bee burrows for others to raise. Males are species-specific - they wait near a nest of their host species, then when a female appears fertilize her and transfer to her pheromones of the host which presumably protect her and her egg from being attacked by the host bee. However, it's the female Nomada that makes the final evaluation of nest suitability. Length 6 mm. Nomada articulata
Nomada maculata: Another cuckoo bee, presumably targeting a different species than N.articulata. Andrena vicina is known to be a target. Length 8 mm. Nomada maculata
Nomada ruficornus: This bee was part of a small swarm of males furiously jockeying for top position among Aurinia saxatilus blooms for a full day. All their wings were worn to a frazzle in the effort. Length 9 mm. Nomada ruficornus male
Camponotus noveboracensis: This ant is common in wet places and moist rotting wood such as in my bog garden. Here one is lugging home part of a Nephrotoma ferruginea. Length 7 mm. Camponotus noveboracensis worker
Camponotus pennsylvanicus: Black Carpenter Ants are omnivorous, eating just about anything except the moist wood that they favour for excavating burrows. In a forest, they chew up tons of wood and turn it into fine sawdust that rots and provides compost for new growth, but you don't want to see them around your home! Whenever I spot one I move it to a local forest away from human structures; length 16 mm. Camponotus pennsylvanicus queen
Formica dakotensis: This Red Wood Ant was introduced in 2015 with the aim of lending a hand to my prized 12 m cedar clump; by late 2017 it had become the dominant species throughout the back gardens. It can enslave most other Formica species, in my case F.fusca. The flat-topped petiole is distinctive; body length 5 mm. Formica dakotensis worker
Formica fusca: Silky Ants are my primary front garden ant. Experts disagree as to whether it is one species or up to half a dozen; meanwhile it just keeps piling sand up around its nest entrances no matter what we say. Worker length 4 mm. Formica fusca
Formica pergandei: These slavemaker ants suddenly appeared in my front garden as a swarm to steal eggs from the resident F.fusca; they'd stayed hidden under the sedum before. Once the F.fusca pupate they'll do grunt work for the F.pergandei; worker length 5 mm. Formica pergandei
Lasius alienus: Cornfield Ants are common in my back garden; the thorax shape is distinctive. Length 2 mm. Lasius alienus
Lasius claviger: This ant was found briefly only in the sandy portion of the alpine garden; length 6 mm. Lasius claviger
Myrmica americana: The wrinkled dorsum separates this species from others locally. Its nests are usually soil chambers at the roots of grasses; the area it was collected was grass when it was collected. Now that I've eliminated grass I no longer see it; length 5 mm. Myrmica americana
Wasps (polyphyletic)
Aleiodes: Mummy wasps lay their eggs within host eggs. When the host caterpillar hatches, so does the wasp. The caterpillar cadaver remains intact and identifiable as the Aleiodes larva feeds and eventually pupates inside the caterpillar leaving the host mummy intact after the adult wasp emerges. Length 4 mm. Aleiodes female
Anoplius: Spider wasps parasitize spiders. This one flew well despite the damage to its wings, but the damage prevented using venation keys to species. Length 11 mm. Anoplius male
Arenetra: This little male wasp doesn't sting. It uses its long antennae to listen for females to mate with; the females use theirs to listen for prey to lay eggs in. Length 20 mm. male Arenetra
Bicyrtes quadrifasciatus: This sand wasp digs small burrows in sand to hold paralyzed Heteroptera to feed its larva. Length 17 mm. Bicyrtes quadrifasciatus
Ceropales maculata: This incredibly long legged spider wasp hunts other spider wasps carrying prey, grabs the prey, lays an egg in it, then lets the original wasp do the work of digging a burrow for it. The C.maculata egg hatches first, hunts down and eats the other wasp's egg, then continues with the spider. What incredible things can be encoded in a single molecule of DNA! Body length 7 mm. Ceropales maculata
Chalybion californicum: This mud-dauber wasp makes frequent visits to the pond to collect water. It flicks its wings distinctively every few seconds while doing so. Length 16 mm. Chalybion californicum
Coelichneumon neocretatus: Length 13 mm. Coelichneumon neocretatus female
Eumenes verticalis: Potter wasps make their nests of mud; this one attaches it to rocks in the nearby meadow. It feeds its larvae on caterpillars. Length 14 mm. Eumenes verticalis
Homolobus truncator: An ichneumon wasp that specializes in armyworms and fruitworms; it's valuable to commercial crop growers. Length 6 mm. Homolobus truncator female
Ichneumonidae: Length 2 mm. Ichneumonidae
Macrocentrus: An ichneumon wasp. Length 3.4 mm. Macrocentrus female
Megarhyssa atrata: This magnificent wasp stopped by briefly, I've never seen one with such a long ovipositor before or since. Ichneumon wasps locate a grub buried deep in rotting wood, drill in to it and lay their egg in it. After the larva has eaten the grub, it knows how to get out. Incredible technology! This one concentrates on Siricid larvae. Ovipositor length 140 mm. Megarhyssa atrata female
Mesostenus gracilis: Length 7 mm. Mesostenus gracilis female
Ophion: These ichneumon wasps are one of the most common parasites of caterpillars here. They are attracted to porch lights. Length 15 mm. Ophion female
Passaloecus cuspidatus: These aphid wasps prefer aphid honeydew and carry aphids back to their nests to feed their larvae. Ivory mandibles are a mark of the genus. Length 6 mm. Passaloecus cuspidatus male
Pelecinus polyturator: This wasp thrusts its ovipositor into soil to detect a grub larva, lays one egg on each. The wasp larva burrows into the beetle larva, killing it, then scavenges remains and pupates there in soil. The long appendage is its abdomen, the ovipositor is quite short. Length 55 mm. Pelecinus polyturator female
Philanthus gibbosus: Beewolves feed their larvae with small bees, especially Halictidae of which there are many locally. Length 8 mm. Philanthus gibbosus
Polistes dominula: European Paper Wasps eat a wide variety of insects. They spend all their time in the garden nosing into the leaf axils of Lilium to collect water, despite the presence of a pond with floating vegetation that all the Vespula use. Length 15 mm. Polistes dominula female
Polistes fuscatus: Northern Paper Wasps prey mostly on caterpillars. As do most paper wasps, they use them solely to feed their larvae, sticking to nectar for their own energy. Length 14 mm. Polistes fuscatus female
Prionyx: The most powerful looking wasp I've ever seen - its mandibles are over 3 mm long and it seems to spend all its time marching along the ground. A juicy grasshopper wouldn't stand a chance in those claws. Length 29 mm. Prionyx female
Sceliphron caementarium: Black And Yellow Mud Daubers build nests of mud in sheltered locations such as under house eaves. Despite its fearsome appearance, it rarely stings anything but spiders which it paralyzes as food for its larvae. Length 26 mm. Sceliphron caementarium
Sphex ichneumoneus: Great Golden Digger wasps feed their larvae with crickets and katydids, but apparently only sip nectar themselves. Length 20 mm. Sphex ichneumoneus
Stenichneumon culpator: An ichneumon wasp whose sole known prey is the larva of Trichoplusia ni, the cabbage looper. Length 12 mm. Stenichneumon culpator male
Therion: This ichneumon wasp patrols a regular route around the garden looking for Lepidoptera and Coleoptera larvae in which to raise its young. It's easily identified in flight by its hanging yellow hind tarsi. Length 27 mm. Therion female
Thyreodon atricolor: A slow flying parasitoid of sphinx moth caterpillars, its laterally flattened abdomen is distinctive. Length 35 mm. Thyreodon atricolor female
Vespula consobrina: Black Jacket workers are unmistakable among Vespula, however unlike their cousin Yellow Jackets, their nests are almost always subterranean in rodent burrows. Length 18 mm. Vespula consobrina
Vespula maculifrons: Eastern Yellow Jacket workers are common associates of picnics and other outdoor food. This one is a queen, massive compared to the usual workers. Only queens survive the winter; as soon as the first batch of workers can collect food, they remain in their nest. Length 18 mm. Vespula maculifrons queen
Sawflies (polyphyletic)
Dolerus nitens: The earliest sawfly to appear here, this one is so covered in sticky Forsythia pollen that it couldn't fly. No other insects visiting Forsythia here have this problem. Length 10 mm. Dolerus nitens
Monostegia abdominalis: These caterpillar-like larvae appear early June in their thousands some years to strip Lysimachia nummularia bare - they also target Oenothera macrocarpa here. They are called sawflies from the action of the females' ovipositors, but are stingless Hymenoptera, wasps without a wasp waist. The larvae are far too numerous to ignore their damage or to turn them into goldfish food, so those easily accessible are picked off into a bucket then squashed underfoot on the driveway. The larvae curl up into a ball and drop as soon as they sense a physical disturbance nearby, and reappear in several waves throughout the summer, so it's an ongoing process. Native to Europe, this species was first recorded in Canada in Ottawa in 1965, feeding on Lysimachia nummularia (also native to Europe); mine is apparently the first record of it also feeding on a native Oenothera. Larvae length 20 mm, adult 8 mm. Monostegia abdominalis
Taxonus rufocinctus: Nothing is known of the hosts or biology of this sawfly. Length 9 mm. Taxonus rufocinctus

John Sankey
other notes on the garden

AntFarm - Myrmecology Forum
Key to eastern Nearctic Vespidae subfamilies
T.B.Mitchell: Bees of the eastern United States (it moves around, Google it)