Friday Bug: Smokey-winged Poplar Aphid.

Chaitophorus  populicola + appreciative flower fly larva

The Smokey-winged Poplar Aphid (Chaitophorus cf populicola Thomas, 1878) has appeared on the Home Bug Garden before under another common name - the Speckled Poplar Aphid - as part of a long post on the rather poor care they receive from their tending black ants. However, they are attractive enough for a Friday Bug and this picture shows what looks like a different kind of syrphid larva feasting away. Perhaps the prevalence of predators of aspen aphids explains why Ives & Wong (1988. Tree and shrub insects of the prairie provinces. Northern Forestry Centre Information Report NOR-X-292) report that none are serious pests except in ornamental plantings. So, unless you have an aspen in your yard (not recommended because the roots seek out water mains), you are free to enjoy this non-pest pest.

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.

Dueling Fabricii: Two Views on Complex Lifecycles

It was 2C this wet and gray Saturday morning, and I guess I could have gotten away with not covering the tomatoes, tomatillos, cukes, etc. last night. It will be cold, wet work uncovering them, so I think I'll leave their rugs on a bit longer and enjoy my breakfast of warm coffee and cold radish. If you think that radishes for breakfast is peculiar, well that's what I thought when I first read about them being a common French breakfast item. I was wrong: crunchy, peppery radishes go well with coffee.

Alas, I don’t grow my own radishes anymore: I have to buy them at the grocery store. The reason is the Striped Flea Beetle Phyllotreta striolata (Fabricius, 1803). You can see one of these above discussing the weather with Black Cherry Aphids Myzus cerasi (Fabricius, 1775) above. Both originated in Eurasia, but have colonized much of the rest of the World. Both were named by the great Danish entomologist and student of Linnaeus, Johan ChristianFabricius. The aphid’s name first appeared in his Systema entomologiæ (1775) and the beetle originally in his Systema eleutheratorum (1801) as Crioceris vittata.

 Fabricius’ ‘System of the Beetles’ (available at Google Books) used Eleutherata for the order of beetles that we now call Coleoptera. I’m not sure why his named didn’t stick – the rules of nomenclature do not apply above the level of superfamily – but he was unlucky with his Crioceris vittata too – the species name was preoccupied and its replacement has wandered through several genera before settling in Phyllotreta. However, Fabricius was able to propose a replacement name in 1803, and so the correct name for the Striped Flea Beetle is Phyllotreta striolata (Fabricius, 1803) (not 1801, as in some references). (The parentheses around the author’s name indicate that the species originally resided in another genus.)

 Thanks to some interesting archeological work excavating a buried privy in Boston, we know that the Striped Flea Beetle has been falling into outhouses in North America at least since 1775 or so (Bain & LeSage 1998). Why are there so many in my backyard? Well, my guess is two-fold: polyphagy and monoculture. The Striped Flea Beetle feeds on a variety of plants in the mustard family (Brassicaceae aka Cruciferae) and so can take advantage of many weedy mustards and the numerous backyard crucifers: radish, turnip, cabbage and similar crops. Also, the Striped Flea Beetle is a major pest in canola in the cooler parts of Alberta (another flea beetle, Phyllotreta cruciferae (Goeze, 1777), is more important further south) (see Dosdall & Mason 2010). Yellow canola fields surround Edmonton in the summer. All of this adds up to a monstrous number of flea beetles.

 Adult flea beetles overwinter in the soil and emerge ravenous in the spring just as the first radish seedlings are germinating. The tiny radish seedlings – just a pair of cotyledons – don’t last long. In contrast, a horseradish that came with the HBG produces large leaves quickly from its perennial taproot and can tolerate a massive amount of damage from its host specialist flea beetle. If I can get the radishes past the cotyledon stage, then I have a hope, but I've failed too many times. I’m trialing turnips this year – planted late and so far not showing much of the typical shot-hole damage. Flea beetles have complex metamorphosis: their grubs live in the soil and feed on roots of the same plants during the summer. The grubs are not considered major pests and for crops like radish and turnip that are soon harvested, they would be trivial. So, if you can beat the adults, you can grow radishes. We will see about turnips.

 Strangely, the Black Cherry Aphid also likes crucifers. You would think that a cherry aphid would stick to cherries, but newly emerged cherry leaves and buds is only their spring food. Although aphids have gradual metamorphosis – their young look more or less like the adults as you can see from the heading picture – they often have a complex life cycle with various winged and apterous forms on two or more host plants. A small dictionary of jargony names been coined for these forms and hosts.

 I’m not a specialist in these bugs, but I’m guessing that the fat black aphids are the fundatrix forms. If so, each developed from a fertilized egg that overwintered on the cherry and are now producing live young parthenogenetically (a long word for without sex). A fundatrix is not going anywhere, nor are her immediate offspring, so they don’t waste any energy producing wings (or males). During the summer, however, winged female aphids develop and disperse away from cherry and on to weedy crucifers or cleavers where they again crank out young without stopping to fool around. In late summer, winged males and females are produced, get it on, and eventually the females leave fertilized eggs on the cherry to spend the winter. This seems to me a complicated way to get from one year to the next, but perhaps all the natural enemies of aphids, the lady bird beetles, lacewings, hoverfly larvae, midge larvae, parasitoid wasps, hunting wasps, gardeners, and assorted diseases, make it worthwhile.

For more information on flea beetles and crucifers see:

Bain, A & LeSage, L (1998) A late seventeenth century occurrence of Phyllotreta striolata (Coleoptera : Chrysomelidae) in North America. Canadian Entomologist 130, 715-719.

Dosdall, Lloyd M. & Mason, Peter G. (2010) Key Pests and Parasitoids of Oilseed Rape or Canola in North America and the Importance of Parasitoids in Integrated Management. pp. 167-213 in Biocontrol-Based Integrated Management of Oilseed Rape Pests.

And for an interesting recent paper on the complex interactions between landscape factors, parasites and predators, ants, and Black Cherry Aphid see:

Stutz, S & Entling, MH (2011) Effects of the landscape context on aphid-ant-predator interactions on cherry trees. Biological Control 57, 37–43.

 

Aculeata Agonistes: Ants, Aphids & Aspen

The Home Bug Garden doesn’t look like the picture above, that is of our Moose Pasture about 55 km to the East as the raven flies, but it may once have. Both are located in the Aspen Parkland biome, named for its dominant tree, Quaking Aspen (aka White Poplar) Populus tremuloides, and its park-like mixture of open grasslands and patches of trees. In the Prairie Provinces of Canada, Aspen Parkland is rich in postglacial water bodies. And, as my late father-in-law pointed out repeatedly, he used to going boating in what is now our neighbourhood when he was a boy.

The prairie parklands occur across a broad stretch of central Canada, but aspen parkland also extends well to the south in the Rockies. South Park in Colorado, made famous by the potty-mouthed cartoon, is just one of many such mixtures of aspen and meadow. Interestingly, parkland is considered a transitional biome between prairie and boreal forest. It’s as if it isn’t really a natural system, but somehow aberrantly refuses to become its destiny: conifer forest if moisture remains high enough and fire frequency low enough or prairie if the opposites occur.

We love aspen, but whenever I find a seedling growing in the HBG, I grub it out. This is an entirely practical behaviour: aspen roots have a reputation for seeking out and clogging water and sewage pipes. Unfortunately, that means we miss out on a lovely tree and all but a passing acquaintance with many of the insects associated with aspen. Not all though, there appears to be at least one aspen-associated aculeate hymenopteron that finds both the Moose Pasture and our yard agreeable: the Black Mound Ant Formica podzolica Francoeur, 1973.

In zoological nomenclature, the year that comes after the author of a species name refers to when the diagnosis of a new species was first published. In this case, I haven’t inverted the 9 and 7 – this species name wasn’t properly sorted out until 1973. Before that it travelled under several names including the widely distributed Formica fusca. Insects tend to be interesting in direct proportion to how much one can learn about them and unless one can first learn their real name, such information as to make them interesting neighbours remains elusive. Ant species are particularly difficult to identify – species level keys are technical, and, well, many ant species tend to look alike. This seems to be especially true of Formica species. In this case, we are indebted to James Glasier for identifying the black ants that caught our attention with their herds of speckled aphids on young aspen as Formica podzolica (misattributions in any other images are mine).

Although the scientific name may be relatively new, people in my neighbourhood have been at war with black mound ants since soon after the first expanses of green lawns rose out of the former slough. Formica podzolica excavates and piles up largish mounds of black clay wherever it feels at home here and no one seems to find lumpy lawns attractive or interesting. In the bush, though, the mounds are an interesting feature and the black ants seem much less aggressive than their red and black neighbours Formica aserva.

I’m less than excited by ants, but no lover of lawns, so generally I leave my ants alone as long as they leave me alone. Unfortunately, ants are infamous for guarding patches of sap-sucking homopterons (aphids, hoppers, and the like). They protect these annoying insects from ‘natural enemies’ such as ladybird beetles, lacewings, and small parasitic wasps. ‘Natural enemy’ is another of those bizarre concepts that has somehow become commonplace. Are there unnatural enemies? Well, I suppose Count Dracula’s cockroach-munching Igor would do. In any case, usually ‘natural enemy’ refers to an arthropod that eats or parasitizes an arthropod that eats something we value. Ants can be natural enemies, but not when they are guarding aphids. By chasing off or killing things that want to eat aphids, ants allow plant lice (= aphids) numbers to rise, the amount of sap they drink to increase, more honeydew to spatter, and sooty molds to cover leaf surfaces. None of this would seem to be good for the plant, but the ants benefit by ‘milking’ the aphids for their honeydew and the aphids are assumed to do better with the guards.

Two things especially intrigued us about the black ants and their aphids on the young aspens, and the first was that the aspen leaves have a pair of nectaries (red spots where the petiole joins the leaf under the leg of the top ant). That plants can produce nectar in flowers to attract pollinators is well known, but nectar-producing glands are not limited to flowers. As a group (and giving an indication that scientists were once surprised to find this out themselves) nectaries not in flowers are called ‘extrafloral’. Ants are known to be attracted to extrafloral nectaries, and one can imagine that having aggressive black ants scuttling around one’s peony buds could be a good thing when some hungry caterpillar was on the prowl for a meal. But why would aspen want ants on their leaves if they end up tending aphids? This particular aphid is a well known pest of aspen – the Poplar Leaf Aphid (aka Speckled Poplar Aphid) Chaitophorus populicola (thanks to Bryan Brunet for the id).

Fossils in the Florissant beds in Colorado demonstrate that members of the genus Populus have had nectaries and been associated with ants and other predatory insects for at least 35 million years (Pemberton 1992. American Journal of Botany 79:1242-1246). Just why aspen have extrafloral nectaries, however, isn’t very clear since they do not seem to influence natural enemy abundance (see Wooly et al. 2007. Annals of Botany 100: 1337–1346). Of course, just calling an insect a natural enemy doesn’t make it useful to a plant (or a gardener). Ambush bugs and crab spiders, for example, make their livings hiding in flowers and eating pollinators.

So perhaps we have good natural enemies that help the plant and get their reward at extrafloral nectaries and other bludgers that just take a sip and go about their not very helpful lives. Life, however, is usually not that simple. For example, the usefulness of extrafloral nectaries may vary with age (younger aspen have proportionately more nectaries than older aspen) and time of year (many nectaries are known to dry up after young leaves have hardened off in early summer). So, ants may be useful for keeping caterpillars away in the spring or on young trees (which have fewer leaves they can afford to lose). Perhaps the ants don’t start farming aphids until after the trees cut off their supply of nectar. Perhaps later in the summer, when leaves will soon be dropping anyway, aspen find it less expensive to let the ants get their sugary rewards second hand from the plant lice than to feed them directly from extrafloral nectaries. There are enough ‘perhapses’ in this simple system to keep a host of scientists busy for years.

Speaking of which, Kailen Mooney & coworkers have found out something interesting about our black ant on pine trees in Colorado. There Formica podzolica herds large aphids in the genus Cinara. I once had a job dissecting Cinara aphids and looking for parasites – 10,000 aphids yielded only 3 parasites, so perhaps our black ant is a good Cinara shepherd (or I was a really bad aphid vivisectionist). However, Mooney found that birds were able to eat both ants and aphids, reducing the latter by 91% (those not eaten dropped to the ground) and causing the ant to look for less dangerous meals. That was good for the pine trees, so birds can be elevated to ‘natural enemies’ here. Black Mound Ants were good for the aphids only when birds weren’t around. But as usual, the story is even more complicated. As well as Black Mound Ants, another species in the same genus, Formica planipilis, also guarded pine aphids. This ant was a better aphid husbander even when birds were around (see Mooney & Mandel 2010. Oikos 119: 874–882 and references therein). I’m starting to feel a little bit sorry for the aphids that Black Mound Ants decide to protect.

This feeling is reinforced by a closer look at our erstwhile aphid farmer: several predatory hoverfly larvae are eating aphids right under the noses of the ants! Apparently the ants are oblivious to the foxes in the hen coop, or perhaps too nervous that a Yellow Warbler may swoop down and eat them to notice. Also, they may be being fooled by the hoverfly larva into thinking the maggots are aphids.  Syrphus ribesii uses its cuticular hydrocarbons to smell/taste like the wooly alder aphid and protect themselves from guarding ants (Lohman et al. 2006. Ecological Entomology 31: 41–51) and this may very well be happening here.

If you can think of being tended by ants as a characteristic of an aphid species, then you could ask the question, we’ll I wonder how many times it evolved in Chaitophorus aphids feeding on poplars and willows? Shingleton & Stern (2003. Molecular Molecular phylogenetic evidence for multiple gains or losses of ant mutualism within the aphid genus Chaitophorus. Molecular Phylogenetics and Evolution 26: 26–35) asked this very question and found that it appears to either have been acquired by several aphids independently or to be a fairly unstable character that has been lost multiple times. Considering this particular association and the results of Mooney and her coworkers, one wonders just how beneficial it is for an aphid to be associated with the Black Mound Ant?

Deleo delirium: Maleficia delenda sunt!

There comes a time in the course of a home bug gardener’s life when events call upon him to take up politically incorrect tools and use them to defend and preserve all he holds dear. Or to paraphrase Cato the Elder: Passer domesticus delendus est! I guess the exclamation point is un-Latin, but then so are periods, and my Latin muse assures me that the passive periphrastic agrees in gender and number with the object that ought to be destroyed. So, no matter what you think Cato said, don’t think delenda or delendum here, but 3rd declension masculine Passer, and IMHO, they all have to go.

Why, you might ask, would someone who claims to be gardening for biodiversity urge that a bird, the alpha and omega of biodiversity, ought to be destroyed? If you are a blue-birder or have a purple martin house, then I guess you already know the bloody murder that house sparrows (HOSP) wreak. If blood and bird bodies don’t bother you, examples of HOSP attacks can be found here. Remember - don't look if you can't stand the sight of bloody birds.

This morning we pulled a dead red-breasted nuthatch from the nest box where they have been relentlessly worried by the larger, alien, invasive, and thuggish HOSP. (I’m making no pretense at being a scientist this morning.) The opening to the box is (deliberately) too small for a house sparrow and all they can do is get their head in far enough to peck. They can’t possibly use the nest box, but being bird-brained, I don’t expect they care. And that’s not all! The bloody HOSPs ate my peas! AHHH! What is a bird introduced to eat insect pests doing eating my garden plants? Bloody bad biology is what. Shades of the cane toad, the HOSP eats few insects and feeds mostly on seeds and plants!

What to do? You probably need a permit to even look at a bird with murderous intent, let alone wring its neck. Ha! Unfortunately for the HOSP, in Alberta they are considered invasive pests, and the Province offers lots of permit-free advice on how to reduce their populations. Firing off shotguns within city limits and spreading poisons aren’t among the things one can do, but trapping is encouraged. Well, more or less. According to Chris Fisher & John Acorn’s “Birds of Alberta”, HOSPs arrived here in 1898 and “People with a dislike for this introduced ‘avian mouse’ go to amazing lengths to combat the species, but House Sparrows are here to stay.” And that certainly seems to be true – it’s hard to find a block in the City where you can’t hear their constant cheaping. It's enough to make you want to squeeze them until their eyes pop out.

And then there are all the other maleficent pests scourging the garden. Formica fusca delenda est! Based on the number of people in Edmonton who whiten the ant mounds in their lawns with boric acid, I suspect the opinion that the black ant must be destroyed is widely held. Since I have no truck with lawns, though, I’ve held them no animosity. After all, ants really are extraordinary superorganisms, industrious, and often fun to watch. These particular ants appear to belong to the Formica fusca group and they can mess up my tiny patches of lawn all they want – but if they want to hang out in my garden, then they’d better be polite. This year they have been extraordinarily rude and their tunneling has already killed a purple sage and a hens-and-chicks and severely damaged a shrub cinquefoil. I tried soaking them with the hose to encourage them to move to a drier site. That does work sometimes, but not this year – a shovel and Dr Doom were required. That made me feel bad, but not so bad when I started looking around at all the collusion between aphids and ants.

Leaf miners, caterpillars, sawflies, spittlebugs, they are all bad, but there are aphids on everything! Aphididae delendae sunt!

A Gallery of Aphid Destruction

I agree with Gardening Zone 3b – where are the ladybugs and lacewings when you need them?

The natural enemies are out there, but I guess they don't like the cold wet weather any more than we do. Slowly they are coming on.


To paraphrase Betty Davis, there comes a time in every gardener's life when the only thing that helps is a glass of champagne. A couple hours with the squirt bottle of soapy water will have to come first though.