Friday, October 19, 2012

Friday Bug: Pine cones, molehills, and gophers

Spruce with cones, snow, and setting sun
The Home Bug Garden is situated in the Aspen Parklands of Alberta, so although spruce trees (White Spruce Picea glauca and Black Spruce Picea mariana) survive in protected areas of the landscape, the natural fire frequency tends to keep them from dominating and favours the patchwork of grasslands and aspen forests that give the parkland region its name. So, for example, if you walk through the Saskatchewan River Valley, you might notice that spruce trees grow mostly on the sheltered, wetter north-facing slopes of the ravine - and in the parks and yards.
Strange "Pine Cone" on my spruce
Actually, you are likely to find many kinds of spruce growing in peoples' yards. The Home Bug Garden has White Spruce, Black Spruce, and (not a native) Colorado Blue Spruce Picea pungens. Like all members of the Pinaceae, spruce produce male and female cones, and each of these cones are distinctive. But our White Spruce produces a third kind of "cone" and although these look very much like cones, they are not 'pine cones' or even spruce cones, but Cooley Spruce Galls caused by an aphid-like bug Adelges cooleyi (Gillette, 1907). 
Developing Cooley Spruce Gall on White Spruce
Blue Spruce are often considered the primary host of the Cooley Spruce Gall 'Aphid', but like many aphids and aphid-like bugs, these insects have a complicated life cycle where they alternate between two different hosts. In this case it is usually a generation on Blue Spruce and then a generation on Douglas Fir (Pseudotsuga menziesii). In Edmonton Blue Spruce does fine in yards, but I can't say I've seen a Doug Fir hereabouts, perhaps because they are only marginally hardy (Zone 4). In any case, only our White Spruce produces spruce galls, so something strange is going on. Most likely a cryptic species or host-specific strain that can get by on just spruce trees is present and it just isn't enough of a pest to have stimulated the research needed to clarify the situation.
Very cone-like gall- but who is it fooling?
In any case, why these tiny bugs make homes that look like cones, I have no idea. Who do they think they are fooling? Well, they do fool most people, even some entomologists the first time they see one, but they don't seem to fool the squirrels. I have yet to see a Red Squirrel feeding on a Cooley Spruce Gall. Perhaps they are too stuffed with spruce seeds, acorns, and baby birds, but I think they know the difference between a gall and a cone.
Do Red Squirrels know a gall from a spruce cone from a pine cone?
Not knowing such a difference or using an  incorrect name are the kinds of things that tend to annoy scientists. So, although Adelges cooleyi was once an aphid (family Aphididae) and called the Cooley Spruce Gall Aphid, these strange aphid-like bugs are better referred to as 'adelgids' now that they have their own family, Adelgidae. Since it is a common name, though, 'aphid' can be argued to be as correct as it needs to be. But the local custom of calling cone-like structures on spruce trees 'pine cones' always leaves me perplexed. Logically, pine cones grow on pines and spruce cones on spruce! Yet, the common name for all cones in my neighbourhood is 'pine cone', no matter what kind of tree it grows on. I don't want to make a mountain out of a molehill, but when I hear 'pine cone' I expect to see one.
Neither mountain nor molehill, but pocket gopher mound
Speaking of molehills, Alberta has none. True moles are small, burrowing mammals related to shrews that feed on insects and worms. Alas, none of the six species of true moles known to live in Canada is found in Alberta. If something  that looks like a molehill is thrown-up in your yard in the Edmonton area, it is a mound created by a pesky, root and top-feeding Northern Pocket Gopher. Therefore, with irrefutable logic, I say this must be a gopher mound! Yet my neighbours looks at me and sadly shake their heads at the ignorance on display, tax dollars wasted, and say 'Gophers don't make mounds, they dig holes!'
If this head could speak, it would declaim: "I am not a gopher!"
"Those are ground squirrels, not gophers, Richardson's Ground Squirrels", I insist to yet more head-shaking. 'Squirrels live in trees. Those are gophers, or you can call them pickets if you want, but they don't make mounds. You can go to the Gopher Hole Museum in Torrington and see for yourself.'  is the response that I get. 
If you can't beat 'em, join 'em: Two Gophers in Torrington, AB
About then, things are starting to get uncomfortable. Either the neighbour thinks I'm an idiot or that I'm pulling their leg. It's time to talk about the weather - something that everyone agrees on. It's as obvious as the snow on your cap or the picket in the pasture.
Gopher, Picket, or if you're argumentative, Ground Squirrel

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