When my family first moved into our home one of the first things I planted was two butterfly bushes next to the back porch. The bushes were on the south side and during the heat of summer blocked the sun from the porch area; they also blocked my view of my neighbors on the other side of the empty lot, and the one across the street who enjoys smoking outside early in the morning during the summer... so early that he generally hasn't put on a shirt yet. Since I too enjoy my morning coffee and cigarette on the porch in the summertime, but do not enjoy the view of him, the butterfly bushes were a welcome addition to my yard.
Sadly, a year later butterfly bushes were deemed noxious weeds in the state of Oregon. They were completely removed from all nurseries and if you live in an area in which they are considered a problem, you should not propagate them and remove all the seed heads at the end of summer to prevent their spread. I love my butterfly bushes, partly because they are so easy to grow, which of course is how they became classified as noxious weeds to start with. Luckily, they look pretty shabby when the flowers die off anyway, so deadheading them isn't an issue. Each fall I take my shears out and slice off everything above the porch rail, then double check that no flower heads are left below that line. They grow back beautifully every spring and attract a multitude of beneficials to my yard.
This post isn't about the bushes however, it's about the bugs. After nearly four years living here my bushes have gone through three summers and I have noticed the changes in visitors to them over those three years.
The first year they were bombarded by little brown skipper butterflies, painted ladies, and swallowtails. Obviously this was what I had planted them for, butterflies! The weather that year was normal for western Oregon, warm wet Spring followed by a hot dry summer.
The second year there were dozens and dozens of hummingbirds, piles of carpenter and bumble bees, a few honeybees. But almost no butterflies at all. The only ones I did see were a few swallowtails. That year the spring stayed cold much longer, and even summer was fairly cool. Everyone complained that their tomatoes wouldn't ripen.
The third year was similar to the second, no skippers, no painted ladies. Even fewer swallowtails. Plenty of hummingbirds and bees. There did seem to be a shift from the carpenter and bumble bees to more honeybees though. Again that year the Spring cold stayed on long after it should have, I still had snap peas producing by the pound in July. The summer was warmer than before, tomatoes ripened on time.
I am very curious about the shift in visitors to the bushes. The butterfly bushes themselves have done great throughout. I did water them daily the first year since they hadn't established a deep root system yet, I suppose the moisture level of the bushes may have attracted more butterflies. I would be very interested to discover what is causing the change in bugs and birds each year. Is it the weather? Or maybe something completely unexpected like a nearby field being sprayed or mowed and killing the butterflies before they hatch? But if so, then why did I get so few bees the first year?
I will keep watching and see if I can work out some pattern in the next few seasons.