Sunday, June 28, 2009

A Short Ode to Pollinators, mostly Bees

I’d like to second Gardening in Zone 3b’s salute to Bug Girl’s Blog for her excellent coverage of National Pollinator’s Week in that large country to our south and especially for her post on ‘Homes for Pollinators’. Devoted readers (reader?, late night insomniac?) may remember that I was lamenting my dearth of information on just that topic a few posts ago. Now I have a wealth of information to digest on how best to make the Home Bug Garden a better place for bees to nest.

Sunday, June 21, 2009

Goodbye to old favourites, native and alien: Winter Kill 2008-9

Rain, glorious rain! Last night, unexpectedly, we got 11.28 mm (yes we have a digital rain gauge, so take the last digit on faith). That’s not even half an inch, but brings our HBG total to 26 mm (just over an inch) since Mayday. Looks like more is on the way too, so although that means our planned Sunday Moose Pasture hiking/canoeing is cancelled, I can plant out the last of the seedlings and catch up on blogging.

Last Fall was very dry, the Winter harsh, and the Spring non-existent. Although the snow cover this Spring was good, it came on late (no snow cover until mid- December) and from 13 December through 9 January every night-time temperature was between -10 and -35 C. The rest of the Winter and Spring experienced repeated bouts of extreme cold with -30 as late as 10 March, the last killing frost (-4) on 22 May (three weeks after the usual last frost date), and the last light frost on 9 June.

The harsh weather is no doubt responsible for the devastation of last Fall’s bulb blow-out (~380 new bulbs went in). Although the established and new crocus, squills, chionodoxa, muscari, and species tulips did well, and quite a few of the new hybrid tulips and daffodils survived and put on quite a display, many were frost blasted and there’s been no sign of others. No sign either of the new Snowdrops (Galanthus nivalis), Checkered Fritillary (Fritillaria meleagris), spendy Lilac Wonder Dog’s Tooth Violet (Erythronium denscanis 'Lilac Wonder') , Spanish Bluebells (Hyacinthoides hispanica), or Grecian Windflowers (Anemone blanda). Not much surprise with the last two – Zone 4-5 plants that have failed before - but the others were all Zone 3, well mulched, watered in, and should have survived (well, maybe not the Lilac Wonder – a bit floppy when they arrived and that is not a good sign with lily bulbs).

The few Alberta native bulbs that I have (Western Wood Lily Lilium philadelphicum, Nodding Onion Allium cernuum) don’t show themselves until late spring. They are just now in bud. None of the bulbous MIAs are ‘native’, so perhaps they just aren’t well adapted to this life. But the established ‘alien’ bulbs seemed to come through pretty well and without them, the HBG would have been pretty bleak this April and May.

The perennials were pretty badly winter whacked too, with 18 no-shows and 3 more that put up a leaf or two, but are on their last roots. Below I’ve divided them into North American Native or ‘Alien’ listed them with the year they went in and their putative USDA Zone rating. There is no obvious pattern by origin: mortality is about equally divided between exotic and North American natives, including 3 plants native to Alberta (a wild bergamot and two sunflowers).

R.I.P. North American Natives Winter 2008-9:
Doppleganger Coneflower, Echinacea purpurea ‘Doppleganger’ 2005 Zone 3
Purple Joe-Pye Weed, Eupatorium purpureum 2008 Zone 3
Wild Bergamot Monarda fistulosa 2003 Zone 3 (AB native)
Garden View Scarlet Bergamot, Monarda didyma ‘Garden View Scarlet’ 2005 Zone 3
Maxmillian Sunflower Helianthus maxmillianii x 2 2004 Zone 3 (AB native)
Sunset Strain' Bitteroot, Lewisia cotyledon 'Sunset Strain' 2008 Zone 4
Purple Leaf Coral Bell, Heuchera americana 'Purple Palace Select' 2005 Zone 4

On the ropes (a couple of leaves left):
Chocolate Mint Foamflower, Tiarella 'Mint Chocolate' 2006 Zone 3
Iron Butterfly Foamflower, Tiarella 'Iron Butterfly' 2007 Zone 3
Ruby Spice Summersweet, Clethra alnifolia 'Ruby Spice' 2007 Zone 4

‘Aliens’ lost this winter:
Fernleaf Yarrow, Achillea filipendulina ‘Cloth of Gold’ 2005 Zone 2
Giant Yarrow, Achillea grandiflora (or maybe Tanacetum macrophyllum) 2005 Zone ?
Monkshood, Aconitum napellus clump 2004 Zone 2
Yellow Loosestrife, Lysimachia punctata ‘Alexander’ x 2 2004 Zone 2
Bronze Garden Mum, Chrysanthemum x morifolium 'Morden Delight' x 2 2006 Zone 3
Siberian Bugloss 'Jack Frost', Brunnera macrophylla 'Jack Frost' 2008 Zone 3
Siberian Bugloss 'Spring Yellow', Brunnera macrophylla 'Spring Yellow' 2008 Zone 3
Chinese Lanterns, Physalis alkekengi franchetii 2008 Zone 2b

Monday, June 8, 2009

March 1, 2159 or Pollinators Not

This morning the clock in the train station claimed it was March 1, 2159. Well maybe it meant that is the earliest we can expect warm weather. In any case, it gives me an excuse to follow up the post on pollinators with one on pollinators not, and display a few more Bug Garden visitors.

Not every arthropod ones finds in a flower is searching for nectar or pollen. Lots of them are there for another kind of feed. That can be interesting, especially if you like predatory insects like the Damsel Bug above, or spiders:

Or it can be disconcerting if you are hoping for fruit or seeds. But the toll that predators take on pollinators is unlikely to be of much importance in yield. Much more insidious are those that have nothing but bad intentions.

I remember how pleasantly surprised I was, that first Bug Garden Spring, at the extraordinary diversity of of sawflies that were visiting flowers. Except for diprionids long ago when I was a forest entomologist, I can't say that I ever had much experience with that branch of the Hymenoptera and I was entranced. Well, now I know better and I've come to an accommodation with most. A few leaves here and there are a small price to pay. The ones that defoliate the currant, columbine, and creeping jenny, though, get a population reduction treatment. They are messy buggers to squish between the fingers, but that's life.

And there are a few of these non-pollinating flower-visitors that are just too attractive not to like, like the tephritid fly below. We have planted lots of goldenrod for the late-summer colour and pollinators, but we don't mind hosting a few gall flies too.

Saturday, June 6, 2009

Gardening for Pollinators meets Lord of the Flies

Another week, another threatened frost: such is Spring in a Zone 3 Bug Garden. Oh well, I should stop whinging and just get on with it. The HBG was first envisioned as a home for pollinators, which I suppose we thought of as mainly bees and butterflies. Well, not really, since at one time or another we have both taught pollination ecology, but embryonic bug garden thoughts aren’t necessarily very deep and butterflies, bees, and flowers was the general idea.

Not that we wanted to see lots of honeybees (another Australian anti-alien bias), but with the spread of the varroa bee mite and the emergence of the mysterious Colony Collapse Disorder, our primary pollinator has been on the ropes for some time now. In Alberta, a harsh climate and marauding bears mean that the only honeybees you are likely to see come from well defended bee keeps. Apparently no one near us has a backyard hive, because Apis mellifera is a rare visitor. That is too bad if you like cherries, saskatoons, apples or other home-grown fruit and vegetables, but there are alternative pollinators that have been attracting attention now that the tried and true honeybee is on the wane. There’s even a web resource page devoted to ‘Alternative Pollinators’ and, although a very high proportion of its links are broken and the functioning links often lead to questionable sources of information, the list supports the assumption that bees + butterflies = alternate pollinators.

Alberta has ‘native’ bees that can hold their own against the climate. Bumblebees (Bombus), leafcutter bees (Megachile), sweat bees (Halictidae), and digger bees (Andrena) are all reasonably diverse here. Our goal was to make the HBG their home by providing a more or less continuous bloom, and to reap our payback in produce. In that, I think we can claim some success, but it is small. Bees need more than flowers, and in particular, they need nesting sites. We did think of this a bit, e.g. planting shrubs with hollow twigs, but the most important of the alternative bee pollinators here are ground nesters and rodent burrows and bare patches of untilled soil aren’t exactly extensive in the HBG. Most of these bees are solitary and having a few dozen nesting in your yard isn’t going to do much for spring flowering fruit, especially since the most efficient of these, the leafcutter and bumblebees, are mostly summer visitors.

Leafcutter bees are a bit of a mixed blessing, since they certainly live up to their name, but they more than pay back the linings of their nests with efficient pollination of most of the veggies in the garden. Unlike most pollinating bees, megachilids collect pollen on their long body hairs and not on special pockets on their hind legs.

Bumblebee colonies take a while to grow and there is a distinct hiatus around now when the first brood must be pupating and the queens taking a well deserved rest. Add to that yet another late, cold spring and the result is cherry trees covered in silent blooms.

Of course bees are not the only pollinators. A variety of other Hymenoptera (ants, sawflies, wasps), beetles, butterflies, and flies come to flowers – or at least to certain kinds of flowers. Spreading, open inflorescences like those found in the carrot family or composites can accommodate a high diversity of insects out for a good feed. Surprisingly, two-winged flies (Diptera) are perhaps the most abundant and diverse of these alternative pollinators. The flower or hover flies (Syrphidae) are perhaps the best known of these floral frequenters. In his "Insects - Their Natural History and Diversity" Steve Marshall says we should treat syrphids as "honorary butterflies" for their bright colours, expert acrobatics, and abundance in familiar environments. Such honours do seem to have been bestowed in the UK, where pocket guides to hoverflies are available and such giants in the pantheon of bug gardeners as Jennifer Owen have done much to document syrphid diversity and abundance in urban gardens. Alas, no such guides or documentation seem to be available here (John, are you listening?).

Many syrphids mimic hymenopterans with a sting such as hornets and bees, which no doubt makes hanging around flowers a bit safer. Beeflies (Bombyliidae) could be said to do the same and often have their mouthparts drawnout into elongate straws for sipping nectar in the deeper flowers. No such advantages in camouflage are apparent in what seem to me to be the creepiest of the dipterons that frequent flowers - blowflies (Calliphoridae), especially species of Lucilia (bottom two pictures in fly plate) that would seem more at home on carrion. Astilbe seems to be especially attractive to these flesh flies.

So if you just want flowers and happy pollinators, and don’t mind a preponderance of flies, think large, open inflorescences like astilbe, goldenrod, butterfly weed, yarrow, daisies, caraway, lovage, and the like. If, however, you want apples, cherries, saskatoons, currants, beans, peas, tomatoes, peppers and anything else that requires some skilled pollination, then you need bees, and bees need a home as well as food. I suppose it is well past time that I started learning what bumble and digger bees need to make a home.