I have two purple leaf sandcherry trees in my yard that I am quite fond of, and I've been battling an aphid outbreak that I am losing badly (tried spraying them off, then soapy water, and then trimming out the more badly infested branches...but the population is still growing rapidly!). So, I was thinking about inviting some ladybugs over for a hearty feast...does anyone know where/if I can buy them in Calgary?

Dave