Thursday, December 22, 2011

What's afoot in the Winter in the Home Bug Garden?

Young Basement Spider Tegenaria domestica
I've always found the first official day of winter somewhat strange, coming as it does, months after winter actually starts. I guess there must be some rhyme or reason to picking the solstice as the beginning of winter instead of say, Winter Hump Day. In much of the world today would be well on the way to Spring. Not in Edmonton, though, we've still a long way to go if previous years are any indication.
A typical March in the Home Bug Garden
So what is the arthropod addict to do with so many more months of winter in the way? Well, our friend John Acorn has come up with the Arthropod Winter Challenge! How many living arthropods can we find in Alberta in the winter? John thinks we can find more arthropod than bird species. Well, inside our house that certainly is true - first look around found three species of arthropods including the half grown Funnel-web Spider (Agelenidae) at the top. That is not quite fair to the birds - we have none to compete - but outside? Yes, there is a cornucopia of arthropods outside that brave the winter weather - but you need to look very closely for them and for many you need to put your nose to the ground.
Microarthropods from a few handfuls of spruce litter under the deep snows of last winter
All gardeners know that a good blanket of snow protects their plants from winter extremes, but even in very cold climates a good snow cover can also capture enough warmth for the tiny animals (microarthropods, nematodes, tardigrades, etc.) and microbes that live in the soil to go about their business. A few degrees above freezing is all they need; but so far, snow has been relatively scarce in Edmonton this winter and so no layer of relative warmth has been trapped. And, while I've enjoyed the less than usual shovelling, it has put a bit of a damper on my response to John's challenge.
A Fairy Wasp (Mymaridae, Polynema sp.) from under last winter's snow
Well, we Edmontonians know that good weather rarely lasts long and I expect that in the New Year I'll have a chance to see quite a bit more snow. I'll take comfort in knowing that under that snow my plants will be safer and there will be tiny arthropods having a good time, like the Fairy Wasp above. This tiny wasp - 0.6 mm long from head to tip of its ovipositor -  is a parasite of the eggs of leafhoppers. Bad news for baby bugs, but good news for the garden.

Saturday, November 26, 2011

A Week for the Bugs: Part I – It’s all in the beak

Very young bugs with thrips, their close relatives

Last week I did something that has become unusual for me: I went to an Entomological Society of America Annual Meeting (its 59th). Yes, I was one of about four thousand bug-obsessed people who descended on Reno, Nevada, for 5 days of presentations on the current state of entomological research in North America (and the World). One bug or another was the buzz for each and every of the 2,200 presentations from entomologists from all over the United States and three dozen other countries. Well, bugs in the common sense, anyway.
A stink bug deploys its all important beak
When I was a child, defining a bug was simple: if it scurried on spiny legs and wasn’t a spider, it was a bug. Such logic sufficed for a child, but as I grew older and began my indoctrination into the entomological mysteries, I learned that there were ‘bugs’ for the common people and ‘true bugs’ for scientists. 
A lightening 'bug' is actually a beetle (Ellychnia corrusca)
 The Heteroptera Latreille, 1810, then an order of about 40,000 species of insects, contains the 'true bugs’. As adults, most heteropterans have ‘different wings’, that is the front pair are hardened and thickened (except towards the tips) and the rear pair are larger and translucent. Heteropterans also have their mouthparts formed into a beak or proboscis for piercing and sucking the juices of insects, plants, or even people.
A seed bug Peritrechus fraternus
The true bugs of my youth included the always creepily interesting assassin bugs and ambush bugs. Then there were the pesky plant bugs, lace bugs, leaf-footed bugs, seed bugs, and the smelly and foul-tasting stink bugs. A trip to a pond or stream revealed armies of water bugs, usually going by other names such as toe-nippers, backswimmers, waterboatmen, and water striders. 
Bug eats bug - note membranous hind wings of victim
 Perhaps the most infamous of true bugs are the bed bugs (family Cimicidae). Along the road to becoming blood-sucking parasites, an ancestor of the bed bugs lost its wings, but otherwise they are typical bugs. Well, so they said, but I never saw one until I was much older. Along the road to becoming a university professor, I lost the Heteroptera as an order, but I gained a world where bed bugs are now common.
Two bed bugs from Queensland with beaks deployed
Heteroptera was good enough to get me through university, and as a suborder sustains me still, but science moves on and today’s true bugs now include the Homoptera (‘same wing’) of my youth. What was once Homoptera have a host of common names. Aphids, plant lice, whiteflies, mealybugs, and scale insects are familiar to anyone who has tried to grow a plant. And then there are the noisy cicadas (aka locusts); bizarre lanternflies; and far too numerous hoppers (plant-, leaf-, tree-, and frog-) and spittlebugs. 
Meet the bugs in spittlebug
 I suppose, 'spittlebug' should now be two words, ‘spittle bug’, at least for those who feel that common names must follow the current scientific wisdom. All bugs with similar piercing-sucking mouthparts, irrespective of their common names, are now subsumed in the older ordinal name Hemiptera (‘half wings’) of Linnaeus, 1758.
A 'throat beak' leafhopper Colladonus belli (Uhler, 1877)
The Homoptera is well and truly gone (see Gullan 1999) and has been replaced by two tongue-twisters. Auchenorrhyncha is, I assume, from the Greek for ‘throat beak’ and referring to an anterior origin of the proboscis. This includes the 42,000 or so species of cicadas, laternflies, and assorted hoppers and spittle bugs.
'Breast-beaked' Giant Lupine Aphids (with thrips)
 The Sternorrhyncha or ‘breast beaks’ have a more posterior proboscis as in the 15,000 or so species of aphids, plant lice, and their scaly, mealy and whitefly relatives. Don’t get too attached to these names, though, because scientific progress may shatter them as well. Some day, a grouchy old throat-beak lover may be bemoaning the Auchenorrhyncha of his youth.
Water strider, currently secure in suborder Heteroptera
Gullan, PJ (1999). "Why the taxon Homoptera does not exist". Entomologica 33: 101–104.

Sunday, November 6, 2011

How to Know a Fly, Part II: Fruit, Pomace, Names & Patterned Wings

Drosophila 'fruit fly' or 'dew fly'?

Tiny flies with red eyes hover over many a bowl of fruit. I suppose that is why we call them fruit flies, but therein reigns imprecision, confusion, and bad wine. I suppose the most well known fruit fly must be Drosophila melanogaster Meigen, 1830, because it inhabits biology and genetics textbooks the world over. My translations of the genus and species names are ‘dew lover’ and ‘black belly’, neither exactly fruity, but seemingly in agreement with other translations. Carl Fredrik Fallén proposed the name Drosophila in 1823 with Musca funebris Fabricius, 1787, as the type species. Funebris is Latin for funeral or death. That would seem to leave us with the equally fruitless ‘Death’s Dew-Lover’ as the type species of the type genus of the 'fruit fly' family Drosophilidae. No wonder, many entomologists, especially if they work in horticulture or quarantine, use ‘Fruit Fly’ for another family: the Tephritidae.
Adult Apple Maggot - a real Fruit Fly (Tephritidae)
Admittedly, although the Tephritidae does contain many economically important pests of fruit, the name may be derived from the Greek for ashes or ash-coloured. Species of Tephritis Griffith & Pidgeon, 1832, do not occur in the Home Bug Garden, but another tephritid fly in the same tribe and with similar habits and similar looks does: Campiglossa albiceps (Loew, 1873). Like species of Tephritis, the maggots of this fly inhabit the 'flowers' (actually heads of many small florets) of plants in the Asteraceae (asters, daisies, goldenrod etc.) and eat the seeds (achenes), but to a botanist achenes are the fruits, so we have some consistency.
Campiglossa albiceps - a tephritid Fruit Fly of ashy mien?
No joy for the etymologist with Tephritidae, but I’m not the only one to find the conjunction of ‘fruit fly’ and Drosophila objectionable. The eminent geneticist MM Green (2002) has a delightful rant in the journal Genetics on the diversity of habitats infested by drosophilid ‘fruit flies’. Perhaps the only thing that ties together the ecology of most species of Drosophila is a fondness for rotten things. Green points out that ‘Pomace Fly’ was the preferred common name in 20th Century genetics texts until the Roaring Twenties when ‘Vinegar Fly’ and the infamous ‘Fruit Fly’ started slugging it out.
Scaptomyza sp. a drosophilid 'fruit fly' that breeds in rotting leaves
As anyone who has allowed Drosophila to get into his or her fermenting mash might know, Vinegar Fly is an all too appropriate name: Drosophila carry the microbes that compete with wine yeasts. Pomice, the mush leftover after fruit hs been juiced, also makes a nice base for a common name. For most of the flies in the family Drosophilidae whose larval habits are known, it is the rot in the fruit  that makes their habitat. The maggots tend to feed on the yeasts and bacteria that develop (probably after having been introduced by adult flies) in spoiled or damage leaves, fruit, nuts, cacti, sap fluxes, mushrooms, and similarly liquefying plant substrates. Perhaps Fallén knew what he was writing about.
Leucophenga sp. a drosophilid 'fruit fly' associated with mushrooms
But even if Fallén was trying to make his name reflect the behaviour of his species, why should we care? Common names are not for scientists. Besides, generalizing about the habits of a family of insects, or even a genus, is likely to lead to error. There are drosophilid maggots that eat fresh water algae, hang out in the gills of land crabs, live in flowers, mine leaves or stems, and even one or two species that attack fresh fruit. Evolution tends towards the opportunistic and if the right opportunity presents itself an insect is likely to try and take it on. An example of opportunism is the drosophilid Chymomyza amoena (Loew, 1862) – a gift from North America to Europe. This fly breeds in a variety of fallen fruit, acorns, and nuts in Eastern North America and is now spreading through apple and chestnut orchards in Europe. Apparently, there are no European ‘fruit flies’ that fill this niche, and our native is happy to oblige (see Burla 1997, Band et al. 2005, Matteson et al. 2007 in references below).
Chymomyza ('juice fly') from AB that breeds in wounds on aspen trunks
The only Chymomyza I’ve seen in Alberta lacks the patterned wings (or boldly contrasting legs – see Eberhard 2002 in refs below) that are used for sexual signaling in both drosophilid and tephritid (and many other) flies and prefers oozing sap to fruit. However, we do have our ‘true’ Fruit Fly: the Apple Maggot (aka Railroad Worm – presumably from the winding trail of the maggot in the fruit) Rhagoletis pomonella (Walsh, 1867) to entertain us. This fly appears to have originated in North America as a maggot in the fruit of hawthorns (genus Crataegus). Like apples, to which they are related, hawthorns have attractive white flowers in the spring (the White Hawthorn is the state flower of Missouri) and red fruit that somewhat resemble tiny apples. When apples started to outnumber hawthorns, some hawthorn flies switched hosts to give us our Apple Maggot. Although watching one strut around in one's garden is not a good sign, they are far more interesting than the cabbage maggots that wreck the broccoli, turnips, and radish.
Rhagoletis pomonella - not a welcome guest, but an attractive one
Well, enough is enough. As usual, what I thought would be a simple post on a few interesting ‘fruit flies’ that might take an hour or so has led to a weekend’s worth of ‘free time’ lost to reading about bugs (instead of doing chores). And I haven’t even gotten to the really interesting things like the ability of some Chymomyza species to survive freezing to −100 °C  (see Koštála et al. 2011) or their use in exploring the ‘Timeless’ gene. I guess there are worse ways to waste one’s time, but just now I’m informed it is time for dinner and I’d better get cooking.
Campiglossa albiceps - a true fruit fly that eats flowers
Band HT. 1995. A note on the sympatric collection of Chymomyza (Diptera: Drosophilidae) in
Virginia's Allegheny Mountains. Great Lakes Entomologist 28(3-4): 217-220.

Band HT; Bachli G; Band RN. 2005. Behavioral constancy for interspecies dependency enables Nearctic Chymomyza amoena (Loew) (Diptera : Drosophilidae) to spread in orchards and forests in Central and Southern Europe. Biological Invasions 7(3): 509-530 DOI: 10.1007/s10530-004-6352-2

Band HT, Band RN & Bachli G. 2003. Nearctic Chymomyza amoena (Loew) is breeding in parasitized chestnuts and domestic apples in Northern Italy and is widespread in Austria. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 76(3-4):307-318.

Burla, Hans. 1997. Natural breeding sites of Chymomyza species (Diptera, Drosophilidae) in Switzerland. Part II. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 70(1-2): 35-41.

Eberhard William G. 2002. Natural history and behavior of Chymomyza mycopelates and C. exophthalma (Diptera: Drosophilidae), and allometry of structures used as signals, weapons, and spore collectors. Canadian Entomologist 134(5):667-687.

Green MM. 2002. It Really Is Not a Fruit Fly. Genetics 162:1-3.

Grimaldi, DA. 1990. A phylogenetic, revised classification of genera in the Drosophilidae (Diptera). Bulletin of the American Museum of Natural History 197: 1–128.

Vladimír Koštála , Helena Zahradníčkováa,& Petr Šimeka. 2011. Hyperprolinemic larvae of the drosophilid fly, Chymomyza costata, survive cryopreservation in liquid nitrogen. PNAS 108(32): 13041–13046.

William Mattson, Henri Vanhanen, Timo Veteli, Sanna Sivonen & Pekka Niemela. 2007. Few immigrant phytophagous insects on woody plants in Europe: legacy of the European crucible? Biological Invasions 9:957–974 DOI 10.1007/s10530-007-9096-y

Sunday, October 30, 2011

A long reach: Daddy-long-legs aka Harvestmen

Meet Phalangium opilio Linnaeus, 1758
I've been trying to decide if a Daddy-long-legs would make a good Halloween costume, but I think the 'face' would be too strange to be scary and the legs far too long and cumbersome for walking around.  Even capturing the legs in a photo of the body can be a problem.
Phalangium opilio has only one generation a year in the Home Bug Garden. At the moment they occur only as eggs hidden in the soil by the ovipositor of the female. In the spring, usually in late May, the tiny young can be seen scurrying around the garden, but one has to look closely to see them. By the end of June they are large enough to be noticed as they nonchalantly wander around feeding on small live insects, dead insects, bits of rotting fruit, and probably from pollen in the flowers they frequent. By the harvest season, they seem to be everywhere, and hence, their other common name.
Daddy-long-legs live up to their name - a front leg, about 6x the length of the body, reaches into the upper left corner of the picture.
Alberta is home to a half dozen or more 'native' species of Opiliones, the order of arachnids to which the Daddy-long-legs belongs, but our species isn't one of them. Phalangium opilio apparently came from Eurasian with the more recent waves of Eurasian colonists and, like the sowbugs in last week's post, is found mostly around people in cities and suburbs. We quite like ours, and can't see any reason not to. They don't bite, they don't bother, and they don't do any damage to the garden. Besides, I was told as a child that if you are lost, catch one, and knock off a leg, it will twitch in the direction of home.
Alien but inoffensive
Several other arthropods are called Daddy-long-legs including flies in the family Tipulidae and spiders in the family Pholcidae such as Pholcus phalangioides  Fuesslin, 1775. These arthropods are easy to tell apart since the spider has a spider's waist and the crane fly has a pair of wings, unlike Phalangium opilio, which has neither waist nor wings at all. We have lots of craneflies in Alberta, but I have yet to see a daddy-long-legs spider. Although this is another of our arthropod synanthropes that have been moved around the world by people, they haven't made it to our basement.
Another kind of daddy-long-legs: Crane Fly (Tipulidae)
A bit of sun, an absence of wind, and the promise (but not yet the reality) of double digit temperatures (in Celsius) this Sunday, perhaps the last positive double digits we will see until April. Good reasons to get out into the garden, or what is left of it. Alas, it is a sad day for the birds - we have taken advantage of the relative warmth to turn off the bubbler, break the crust of ice, and pull the pump and filter out of the pond. The birds will continue to return for a couple of days, peering down the fountain hole, but no more water will be forthcoming until next spring.

Saturday, October 22, 2011

Porcellio spinicornis Say: The Spine-horned Little Pigbug that didn’t belong

A cluster of Edmontonian Sowbugs aka Woodlice when they aren't in a yard

Swans were winging their way overhead this morning, but the chill and the wind have kept what winged-insects are still about well hidden. It’s that time of the year for raking leaves, cutting down frost withered vines, composting rotting green tomatoes, and emptying pots of browned flowers. Moving pots, though, does give one the chance to observe some of the less obtrusive arthropods that skulk under them and scatter to any convenient crevice when disturbed. Among the skittering is one I have been meaning to write about for awhile, but never had the time to sit down and work out its proper name.
A freshly moulted Sowbug in an Edmonton backyard
What I did know was that the small, flat arthropods that were so common underneath things in my backyard were members of the crustacean order Isopoda (they have 7 pairs of legs). In Australia, I would have called these animals 'slaters', but when I was a kid in another land, I called them ‘so-bugs’. I got the common name, sowbugs, from a book and assumed it had something to do with them being scattered across the ground like sown grain. When you turned over a rock or board or moved a pot, they did sort of look like scattering grains, so the name seemed to make sense. But much to my embarrassment, as a young entomology student I learned that everyone else in North America called them ‘saughbugs’ after  fancied resemblance to female pigs! Some sowbugs can roll into a ball (conglobation) when disturbed, and these are called pillbugs for a reason that was obvious even to me.
Conglobated Pillbug (probably Armadillidium vulgare) from BC
Well, whatever you call them, sowbugs are one of the more successful lineages of land animals. We usually think of crustaceans (crabs, lobsters, crayfish, shrimp, prawns, and the like) as being inhabitants of the oceans, but most of the 3600 described species of the suborder Oniscidea are fully terrestrial.  An exception are members of the family Ligiidae that live an amphibious existence along the coast (see Ted MacRae’s great post). The earliest known fully terrestrial isopods are Eocene fossils from after the great extinction event that removed the dinosaurs inter alia at the end of the Cretaceous Period. Perhaps one or more ancestral amphibious sowbug found life on land easy in the brave new Eocene world, but in any case, their descendants have colonized most of the landmasses on earth (Antarctica and a few small islands excepted). Mostly they all do the same thing – eat decomposing plant  matter and so are ‘good bugs’, at least to any gardener that likes a healthy garden.
Sowbug lurking in a crevice - something they do very well
Until about 9-10,000 years ago, Alberta was pretty much free of any animal life, let alone sowbugs. Any that once lived here would have been ground to dust by the glaciers and this state of affairs seems to have held until recently. My wife, who grew up in Edmonton and enjoyed turning over rocks to see what lived underneath, claims there were no sowbugs here when she was a child. Our friend John Acorn, a dedicated Albertan naturalist, supports her claim. Jass & Klausmeier (2000) list no records, whatsoever, of terrestrial isopods from Alberta. So, what is this slater living in my backyard?
Antennal spines (arrows), black head, dark midline stripe, yellow spots, arrangement of lungs, and other characters support Porcellio spinicornis Say, 1818
Answering that question is what took so much time; however, thanks to an excellent key by Stephen Hopkin (1991), the invaluable BugGuide, the University of Alberta library, and a certain terrier-like attitude to unnamed bugs by both Mr & Mrs HBG, we now have an answer. Back in 1818, Thomas Say, the great American naturalist, conchologist, entomologist, and nascent explorer, published a paper in the Journal of the Academy of Natural Science (Philadelphia) on new species of Crustacea he had discovered in the United States. Among these hard shellfish was one whose ancestors left the oceans long ago and had spread far and wide on land: Porcellio spinicornis Say, 1818. Apparently, Say was impressed by the dorsal ridges on the second and third antennal segments that ended in stout spines (hence spini [L. spine] corn- [L. horn, or in this case, antenna]) and no doubt the attractive colours in the living animals. Presumably, Pierre André Latreille, who in 1804 named the genus with the Latin for a small pig was channeling the sowbug meme. However, this Spine-horned Little Pigbug should not be confused with another widely distributed sowbug, the Common Woodlouse Oniscus asellus L., 1758, a species that I have yet to see in Alberta.
Common Woodlouse from BC
Say appears to be wrong about the origin of his woodlouse. Today Porcellio spinicornis Say is considered one of about three dozen species of terrestrial isopods that have been introduced into the Americas from the ‘Old World’. This must have happened very early on, but now this species can be found in much of North America including Canada (although not officially in Alberta). Some pest control operators like sowbugs, because fussy homeowners find them distressing and are willing to spend money to have them sprayed into oblivion. I don’t see why. Although they do scurry about and hide under pots and the like, they appear to eat nothing except plant matter that has died and been overgrown with fungi and bacteria. This seems fine if they keep to cities and suburbia and so far, that is what they seem to do.


Hopkin SP. 1991. A key to the woodlice of Britain and Ireland. Field Studies Council AIDGAP Guides 204

Jass J & B Klausmeier. 2000. Endemics and immigrants: North American terrestrial isopods (Isopoda, Oniscidea) north of Mexico. Crustaceana 73 (7): 771-799.

Leistikow A & Wägele JW 1999. Checklist of the terrestrial isopods of the new world. (Crustacea, Isopoda, Oniscidea). Revta bras. Zool. 16 (1): 1 - 72,1 999

Lindroth CH. 1957. The Faunal connections between Europe and North America. Biodiversity Heritage Library

McQueen DJ. 1976. Porcellio spinicornis Say (Isopoda) demography. II. A comparison between field and laboratory data. Can. J. Zool. 54: 825-842.

McQueen DJ & JS Carnio. 1974. A laboratory study of the effects of some climatic factors on the demography of the terrestrial isopod Porcellio spinicornis Say. Can. J . Zool. 52: 599-611.

Say, T., 1818. An account of the Crustacea of the United States. Journal of the Academy of Natural Science Philadelphia, 1: 235-253, 313-319, 374-401, 423-458.

Schmalfuss H. (2003): World catalog of terrestrial isopods (Isopoda: Oniscidea). Stuttgarter Beiträge zur Naturkunde, Serie A, Nr. 654: 341 pp.

Schmidt C. 2008. Phylogeny of the Terrestrial Isopoda (Oniscidea): a Review. Arthropod Systematics & Phylogeny 66(2): 191-226.

Friday, October 14, 2011

Wine, Bacon, and Beetles

A beetle that appreciates wine - the Picnic Beetle
Autumn has certainly settled in and as the leaves colour and fall, the other garden colours also fade away. Gone are the butterflies, yellowjackets, bumble bees, and flower flies. A few flowers still linger in spots sheltered from the frost, but only honeybees visit them. If you search around, there are still plenty of grey flies and midges. A small swarm of Dixella midges were dancing near the pond on a warm evening just last week. But the drabness of winter is clearly drawing neigh.
Glischrochilus fasciatus (Olivier, 1790)
So a colourful beetle is a welcome visitor, even if it seems intent on drowning in one's wine. Glischrochilus fasciatus (Olivier, 1790) has a number of boring common names based on its spots, but my favourite nom de bug is the Picnic Beetle. A member of the Sap Beetle family (Nitidulidae), well known for their fondness for fermenting plant juices, the Picnic Beetle often lives up to its name and pesters those of us that quaff our fermented drinks outdoors. The adult beetles overwinter, so their autumnal draughts are probably the last fun they'll have until the spring.
Dermestes lardarius - aka Bacon or Larder Beetle
Another, less colourful beetle, has also been around, but is not so welcome. Dermestes lardarius was named by Linnaeus himself in 1758 and now occurs around the world in people's homes. The most common common name seems to be the Larder Beetle, but I prefer the Bacon Beetle. Any beetle that likes bacon must have some redeeming qualities. Like the Picnic Beetle, the Bacon Beetle overwinters as an adult. The larvae prefer high protein foods and commonly dine on meat, pet food, and dead insects. I imagine they miss the good old days when hams and bacons were hung near the fireplace, but they seem to do just fine on what they can find now.
Hyssopus officinalis flowers into October

Friday, October 7, 2011

Bumbling with Bombus: I’m a bad, bad, bee

Indiscriminate Cuckoo Bumblebee Queen
September was mostly a dry and sunny month in Edmonton with the Home Bug Garden dipping to freezing only twice and no lower than 1.3 C at the downtown airport. So, garden flowers, even the monkshoods that never quite manage to flower before being killed by frost, and a few of the insects that visit them (especially hover flies) have persisted unusually long this autumn. Outside the heat island of the City, though, we had hard frosts (-4) at the Moose Pasture by mid-September. Frost and dryness put end to most of the flowers and only a few asters were still blooming. Well, wild asters and the coneflower (Echinacea purpurea) we had planted on the edge of our small garden plot.
A usually too late bloomer Aconitum divergens
 We didn’t expect much on our mid-September trip except grasshoppers and dragonflies. So my wife didn’t bring her fancy camera, just the point-and-shoot Canon Powershot SX20 that she uses for landscape photos. That caught us up short, because our coneflower, was hosting a small swarm of bumblebees. Mostly these were queens of the Half-black Bumblebee (Bombus (Pyrobombus) vagans Smith, 1854) stocking up for the winter hibernation and a couple of drones hanging on for dear life. But one of the large black and yellow bees looked a bit different – and so it was, an Indiscriminate Cuckoo Bumblebee Bombus (Psithyrus) insularis (Smith, 1861).
Moose Pasture in mid-September 2011
 When bumblebee queens start their nests in the spring, mostly they just work hard to get their colonies growing. But sometimes a queen who has lost her nest or failed to start one will enter the colony of another and try to kill the resident queen and take over. This is called colony usurpation or queen supercedure. Presumably environmental factors such as spring weather and the availability of nest sites influence how often this happens, but usurpation can be common. As many as 20 dead queens have been found in a single nest (Kearns & Thomson 2001) indicating fierce competition for a site. Often a homeless queen tries to steal the nest of another of her species, but other Bombus species are also fair game. Some time in the distant past, one group of bumblebees gave up on raising their own workers and became obligate social parasites – invading nests, killing queens, and co-opting the resident workers to raise broods of cuckoo queens and drones. Compared to queens of other subgenera of Bombus, cuckoos in the subgenus Psithyrus are more heavily armoured, have larger mandibles, a longer curved sting, a more elaborate venom apparatus, more ovarioles, and lay smaller eggs (Fischer & Sampson 1992). So, Psithyrus species seem very well adapted to their nefarious activities.
Note yellow hairs on head, black on base of abdomen
 Our Bombus (Psithyrus) species has acquired the common name of ‘Indescriminate’ and the data that GA Hobbs gathered in the 1960s supports the name. Hobbs worked at what is now known as the Lethbridge Research Centre and most of his data is from the southern part of the Province. He found that what was then known as Psithyrus insularis was successful in usurping the nests of Bombus (Bombias) nevadensis, Bombus (Thoracobombus) fervidus (as B. (Fervidobombus) californicus), Bombus (Subterraneobombus) appositus, Bombus (Bombus) occidentalis and terricola, and many species of Bombus (Pyrobombus). For Pyrobombus, the most diverse and abundant Bombus in the Edmonton area, Hobbs (1967) found 97/191 (51%) of the nests harboured the social parasite. This seems very high, but is similar to what has been reported for European bumblebees parasitized by another species of Bombus (Psithyrus) (Erler & Lattorff 2010). If you think bumblebees are good, and you worry about their conservation, then this may be a bad, bad, bee.
Bombus (Psithyrus) insularis - Indiscriminate Cuckoo Bee
Craig CH. 1953. Psithyrus insularis (Sm.) in a Nest of Bombus ternarius Say (Hymenoptera : Bombidae). Canadian Entomologist 85: 311-312.
Erler S & Lattorff HMG. 2010. The degree of parasitism of the bumblebee (Bombus terrestris) by cuckoo bumblebees (Bombus (Psithyrus) vestalis). Insectes Sociaux 210: 371-377. 30-100%, 33-50%
Fischer RM & Sampson BJ. 1992. Morphological specializations of the bumble bee social parasite Psithyrus ashtoni (Cresson) (Hymenoptera: Apidae). Canadian Entomologist 124: 69-77.
Hobbs GA. 1965. Ecology of Species of Bombus Latr. (Hymenoptera: Apidae) in Southern Alberta. II. Subgenus Bombias Robt. Canadian Entomologist 97: 120-128.
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