Summer Flies & My Favourite Weed

August is going out on a cold and dreary note. The dropping temperatures and yellowing leaves remind us that soon the Frost Monster will be slashing at the Home Bug Garden plants and animals. The first to go will be the South American Solanaceae: tomatoes, tomatillos, ground cherries, potatoes, and peppers. Tonight it is supposed to drop to between 5 and 3 C, depending on which Edmonton airport you live closest to (HBG is midway between). And I’m eyeing all those green tomatoes and yellow peppers and wondering how optimistic I should be.

One plant that won’t pay much attention to the Frost Monster will be my favourite weed: the thallus forming liverwort Marchantia polymorpha Linnaeus. Many liverworts look much like the mosses with which they used to be grouped, but marchantia looks more like a lurid green lichen with tentacles (females) or parasols (males) than your typical bryophyte. It does well on wet soil and may annoy greenhouse owners and some gardeners.

I suppose if I were trying to grow ferns but all I ended up with was more marchantia, then I might be annoyed too. As it is, I chop it up when it is in the way and try to appreciate it when it is growing in some more appropriate space, like around the base of the bird bath.

 Some people think that flies are pesky too, but other than ineffectively swatting at an importune muscid or calliphorid we try to get along with the higher Diptera.

Flies will likely be the first active insects next spring, so I think I’ll say goodbye to summer by revisiting some of the smaller and more interesting flies of the year.

 And lets not forget the bugs that will soon be memories too.

Mugging with Monochamus

I’ve been religiously reading Compound Eye and trying to improve my photographic technique while sticking with my convenient point-and-shoot camera. I think I’m getting a few pictures that speak more to the strengths of my camera than to my desire to document a species, as with the long-horned beetle above and its impressive antennae. But I had a bit of a letdown this morning when I saw that the Edmonton Journal article on the White-tailed Bumblebee has eschewed my pictures in favour of my wife’s (although still attributing the picture to me). Oh well, my bee pictures were for documentation anyway, but this beetle view was for fun.

 One advantage of a point-and-shoot is one-handed snaps as above, a more difficult feat with a heavy SLR. The White-spotted Sawyer Beetle, Monochamus scutellatus (Say, 1824), is probably better known in Alberta as the Tar Sands or Oil Sands Beetle. When a conifer is damaged, a variety of volatile chemicals are released, and sensors in the long antennae allow the female beetles to track down a good tree in which to lay their eggs. The larvae then burrow in the wood for a couple of years. Apparently the tar sands emit similar turpentiny smells and keep the beetles a buzz.

 Sawyer beetles are rather large: the White-spotted Sawyer above was about 2.5 cm long with an antennal span of 7-8 cm. I once had a job sawing off all the limbs, one by one, from the ground to the top of live, standing fir trees. I still remember the shock when large sawyer beetles would crash into me while I was dangling 30 or 40 feet above the ground. It did make one appreciate their safety ropes. The beetles may have appreciated the results of our work – a limbless tree that looked more like a telephone pole – but I don’t think the poor poplar branch boring longhorn beetle (Oberea quadricallosa LeConte) above will be able to appreciate much of anything without its antennae. Who knows what disaster befell the beetle, but it may have been ants tending aphids and objecting to its feeding on a poplar leaf. As you may note from the clarity of the picture, this one came from my wife's Nikon SLR.

Bumbling with Bombus: the late lucorum

A new insect in the Home Bug Garden, unless it is a new mosquito, is always a welcome occurrence. But when it comes in a group that we thought we knew pretty well, it is especially interesting. Last week this largish white-tailed bee arrived - just after I had just told a colleague in Calgary, that we don't have them here in the HBG.

You would think that bumble bees (aka bumblebees) would be fairly well known. They are large, brightly coloured, industrious, more or less likable insects and well known for being good pollinators. Many dozens, perhaps hundreds, of scientific studies have been conducted on North American bumble bees and one would hope that the scientists were sure of their bee species. However, bumble bee colours are not to please us, but to warn potential predators that they taste terrible and have a large sting to boot. It helps to get the message across to birds and other insectivores when bees look more or less alike - hence the convergence in colour patterns that makes, for example the tricoloured bumble bees, so difficult to tell apart. This is officially known as Müllerian Mimicry (as opposed to Batesian Mimcry where tasty, harmless animals tend to look like nastier ones) and it occurs among the white-tailed Bombus (Bombus) species too.

The complex of white-tailed bumble bees has variously been called the terrestris-complex or the lucorum-complex after two well known Eurasian bumble bees. However, in 1990 two Swiss scientists and one from Calgary got together to show that the 'lucorum' in North America had different enzyme loci from European lucorum, but ones identical to the more mysterious Bombus moderatus Cresson, 1863, known from Alaska, the Yukon, the old Northwest Territories, northern British Columbia and down the Rockies to Jasper and Banff (the southernmost record) in Alberta. More recently it has shown up in Calgary and is featured at Robert Bercha's Insects of Alberta. Now this bee seems to have colonized Edmonton.


Thus we seem to have a name for our mystery Bombus - but unfortunately B. moderatus was identical in the enzyme loci to several other named Bombus species including one with an older name Bombus cryptarum (Fabricius, 1775). More recent studies by Andreas Bertsch and his colleagues have shown that Bombus moderatus from Alaska and Alberta and B. cryptarum from Europe have very similar, although not identical, 'barcodes' (a region of the mitochondrial gene cytochrome oxidase I). So, eventually what was once known as Bombus lucorum and now probably better called Bombus moderatus, may one day be called Bombus cryptarum.


Update: The BugWhisperer has found Bombus moderatus in his garden in Edmonton. Also, a friend collected several males to the west of Devon last Friday (19 August 2011). That is a probably a good sign, or at least will be if new queens of B. moderatus soon follow. Yesterday I noticed a number of males of what may be Bombus rufocinctus at my fireweed. I guess the bees think summer is coming to an end.


References

Berstch A. 2010. A phylogenetic framework for the bumblebee species of the subgenus Bombus sensu stricto based on mitochondrial DNA markers, with a short description of the neglected taxon B. minshanicola Bischoff, 1936 n. status. Beiträge zur Entomologie 60: 471-487.

Scholl A, Obrecht E & Owen R. 1990. The genetic relationship between Bombus moderatus Cresson and the Bombus lucorum auct. species complex Hymenoptera: Apidae). Can. J. Zool. 68: 2264-2268.

Update: Thanks to Cory Sheffield for pointing out this beautifully written article by Robin Owen at Mount Royal on Bombus moderatus.

Aculeata Agonistes: Yellow-faced Bees (Hylaeus)

Hylaeus is a large genus (~900 species) of mostly very small bees (5-6 mm long is common) in the family Colletidae. They are worldwide in distribution and especially diverse in temperate to subtropical Australia. Hylaeus also do reasonably well in the temperate to boreal areas of North America (55 species north of Mexico). Tatiana Romankova of the Royal Ontario Museum estimated that at least 13 species of Hylaeus occur in Ontario (Romankova 2007) and 7 of these species may also occur in Alberta. She provides a key to the species in Ontario, but I’m not sure how useful it would be here, since we probably also have species not represented in the East.

Most Hylaeus nest in cavities such as hollow stems, beetle galleries, or nail holes in wood. So, planting shrubs with hollow stems or making drilled-bee homes should help to attract them to your yard. Some species have more specific nesting sites such as empty plant galls or the cavities in volcanic rock (Michener 2007). The latter habit is probably useful in Hawaii where Hylaeus is the only genus of native bees. Sixty different species are known in the Hawaiian Islands today and they appear to have arisen from the successful colonization of the Island of Hawaii by one species (probably from Japan or another part of eastern Asia) about a half million years ago (Magnacca & Danforth 2006).

Hylaeus are very unusual bees. They have few of the branched body hairs that are the definitive character that separates bees from their close relatives the hunting wasps. They also lack the specialized tufts of hairs (scopa) or leg basket (corbicula) that other bees use to collect pollen. In fact, they are so wasp-like that one species has been used to fool entomologists on a Monday Night Mystery at the Myrmecos Blog. Bees are just a branch of the hunting wasp lineage and so the ur-bee must have been rather waspish.

Are Hylaeus, then, among the most primitive bees? Not according to a recent molecular phylogeny of the Colletidae (Almeida & Danforth 2009). Instead, Hylaeus species appear to be relatively recently derived within the Colletidae and their particularly un-bee-like appearance and habits are relatively recent evolutionary innovations. This includes behaviours such as ingesting both pollen and nectar that they carry in their crop and use to provision their nests with the liquid mixture. This is very similar to what Pollen Wasps (relatives of the yellow jackets: Vespidae, Masarinae) do, but both cases seem to be parallel derived behaviours and not vestiges of the proto-bee.

Hylaeus species are known to visit a variety of flowers for nectar, and since the pollen is not easily collected out of the bees, it had been assumed that the bees are pollen generalists as well. However, Virginia Scott (1997) studied three species of Hylaeus in Michigan and found that all were specialized on pollen from members of the rose family (Rosaceae). The hard outer coating of pollen survives digestion and Dr Scott had the fun job of collecting Hylaeus larval fecal pellets, making slide mounts, and identifying the pollen. Much of scientific research consists of equally fun jobs, but I hope Dr Scott developed an appreciation for the wonderful form of pollen grains. In any case, hers is the only good study on the pollen habits of Hylaeus that I could find. At her study site cinquefoils (Potentilla), blackberry and its relatives (Rubus), and meadowsweets (Spiraea) were the preferred foods.

The Home Bug Garden has many Rosaceae, including representatives of all three genera, at least in the old sense of Spiraea which included goatsbeards (Aruncus) and Queen-of-the-prairie (Filipendula). We also have many bushes with hollow stems, holes drilled into logs and boards, and are graced by some of The BugWhisperer’s experimental bee hotels. Perhaps all of these have come together in this rather dreary summer to make the Home Bug Garden a good habitat for Hylaeus.

References:

Almeida EAB & Danforth BN. 2009. Phylogeny of colletid bees (Hymenoptera: Colletidae) inferred from four nuclear genes. Molecular Phylogenetics & Evolution 50: 290–309.

Magnacca KN & Danforth BN. 2006. Evolution and biogeography of native Hawaiian Hylaeus bees (Hymenoptera: Colletidae). Cladistics 22: 393–411

Michener CD. 2007. The Bees of the World, 2nd Ed. The John Hopkins University

Press.

Romankova TG. 2007. Bees of the genus Hylaeus of Ontario (Hymenoptera: Apoidea: Colletidae). J. ent. Soc. Ont. 138: 137–154.

Scott V. 1997. Pollen selection by three species of Hylaeus in Michgan. Journal of the Kansas Entomological Society suppl. (1996): 195-200.

Hornworm or what a hummingbird moth looks like before its metamorphosis

Back in 2005, the year after the Home Bug Garden got its first major additions of expensive perennials (and the year after most were striped half bare of leaves by the hail from the two '1 in 200 year storms'), our new flowers were visited by several Hummingbird Clearwing Moths (Hemaris thysbe Fabricius, 1775). The moths proved too fast for our cameras, but other photographers at BugGuide have posted several excellent pictures. The day-flying moths look more like giant bumblebees to me than hummingbirds, but they can hover very well and are the right size for hummers.

A few weeks later, we were aghast when we noticed two inch-long green horned-devils stripping our struggling highbush cranberry and nannyberry bushes. Urr, arghh - the first real challenge to our pretense of gardening for bugs. We decided on a compromise in this first skirmish and deported half the caterpillars to outside the yard to fend for themselves and let the other half feed away to pupation. It turns out we need not have worried so much about our highbush cranberries - all but one scraggly survivor have been destroyed by another day-flying moth, Synanthedon fatifera, the viburnum crown borer. The adults appear to be mimicking a spider wasp in this case. The caterpillars bored in the crowns of our highbush cranberries killing a third to a half of the canes each year until I had to grub out what rotten bits of persistent crown were left.

Fortunately, the borers don't seem to be interested in our nannyberry (now nearly 3 m tall), nor did the hummingbird moth. But when a friend on AlbertaBugs pointed out that he had the caterpillars on his viburna, we checked and lo and behold we have them again. This time we will let them eat all they want - there are lots of leaves and only a handful of hornworms - and just be happy they are still around.

As well as welcoming back an interesting bug, this posting was designed to follow-up on what I learned at a post at Alex Wild's new blog at Scientific American, The Compound Eye. Among other things, Alex boldly states that to post an image to its best effect "Every blogger should know their column width, in pixels. " I don't seem to be clever or persistent enough to find this information on my blog, but a little experimenting indicates that a 600 pixel wide image as above is not auto-crunched by Blogger. I highly recommend The Compound Eye to anyone interested in getting the most out of their insect photography.

The Home Bug Garden in July: Rain, Mosquitoes & Bumblebees

 My apologies to any regular readers for the long dearth in postings. This has been a miserably cool and wet summer in the Edmonton region, and along with the drain of a minor illness and the usual overwhelming nature of the field season, energy for any extra musings has been low. There have been lots of insects in the HBG, but mostly millions of mosquitoes (I’ve identified 11 different species so far).

 Even with the best intentions, though, and an amazement at how many different kinds have been seeking my blood, it is difficult to summon the energy to write appreciatively about mosquitoes and even more difficult to identify them from a picture. Instead, one must kill them carefully – no swatting or the hairs and scales needed to determine species will be knocked off – and take them to a microscope and an identification tool. If you live in Canada, the Canadian Journal of Arthropod Identification has an excellent pictorial key produced by Aynsley Thielman and Fiona Hunter of Brock Univerity in Ontario. 

 Only female mosquitoes drink our blood and only when they can. Both sexes will feed on nectar and other sources of sugary food such as honeydew or damaged fruit. Cool wet weather also favours aphids, so there is plenty of honeydew around, and discourages harvesting cherries from wet dripping trees. I haven’t actually seen any mosquitoes feeding on the cherries damaged by the house sparrows or blown to the ground by the storms, but it wouldn’t surprise me.

 The unending rains and mostly low daytime temperatures may have found favour with the mosquitoes and aphids, but I suspect many of the other insects have been reacting to the La Niña weather more like I do. The number and variety of bees has seemed to be unusually low and less energetic than usual. One bit of good news: the umbrella over the mud dauber nest seems to have been a success. The Ancistrocerus waldeni has covered the entire face of the rock with cells and, at least as of last Tuesday, she could still be seen working away.

 Bumblebees, of course, are able to fly and forage under a wider range of weather than most other bees, and the HBG Bombus have been apparent whenever the rain wasn’t actually falling. The diversity is similar to previous years, but the numbers may be lower.

 The Yellow-banded Bumblebee (Bombus terricola) was apparent early in the season, but seems rare now. A variety of tricoloured bumblebee queens (Bombus ternarius, huntii, centralis) began showing up not long after that and workers of “The Tricoloured Bumblebee” (B. ternarius) and B. centralis (which seems to have missed out on a common name) are still foraging along with numerous Half-black Bumblebees (Bombus vagans), which show up somewhat later. Finally, a large and mysterious mostly yellow queen began foraging in late July (possibly a Bombus (Bombias) species).

 The life of a bumblebee worker is short and sweet. Well, certainly short (2-4 weeks is commonly reported), and I hope the nectar helps to make the constant toil sweet. As well as working themselves to death, bumblebees have numerous parasites, predators, and diseases. Ailing workers are starting to show up in the HBG. There is a tendency to assume that some poison is at work here, but we rarely used chemicals and the City certainly hasn’t been spraying for adult mosquitoes. So, it is more likely a ‘natural’ death that is starting to claim workers.

 One common and swift end for bumblebee workers is being bitten in the neck by crab spiders. Misumena vatia is the common one in the HBG. Although I feel protective about my bees, I usually let the spiders go about their business. On Canada Day, though, my wife took a picture of one such spider bee-feast and noticed that the dined-upon bee had a couple of mites hanging out on its shoulder. I immediately dashed out and wrestled the bee away from the spider. The spider was definitely upset, the mites seemingly oblivious, but I was delighted because it gave me an opportunity to use an online key for something other than a mosquito. Barry OConnor and Pavel Klimov at the University of Michigan provide this resource for bee mites of many kinds. The long and the short of it: these two unfortunate victims were Parasitellus talparum (Oudemans, 1913). Originally described from the nest of a mole, these mites are probably predators of other small invertebrates in the bee nests and so probably good for the bees.

For more about bumblebee mites in Alberta:

Richards LA & KW Richards. 1976. Parasitid mites associated with bumblebees in Alberta, Canada (Acarina: Parasitidae; Hymenoptera: Apidae). II. Biology. University of Kansas Science Bulletin. 51(1): 1-18.