I was unconcerned when I first noticed an infestation of aphids on seedpods of the Swamp milkweed (Asclepias incarnata, below). What harm could be done to this vigorous native? Probably none, and I planned to let nature takes its course.
Its course, as it turns out, was to attract beetles that have quickly stripped aphids from several sets of seedpods. I expect all aphids will be gone in another few days without intervention on my part. Given the few disease and pest problems in this garden, I suspect that natural controls occur many more times than I’m able to witness.
Certainly, I notice dragonflies darting across the koi pond, and with the notable lack of Tiger mosquitoes in the vicinity, I suspect dragonflies are the reason. While much of the zipping about of the dragonfly defines its territory, other movements are predatory, though the violence of the capture of the mosquito occurs at a speed that I cannot see.
This afternoon, I noticed the start of webworms in the Silver Cloud redbuds (Cercis canadensis ‘Silver Cloud’, below). To the best of my recall, the stinging caterpillar of the White Flannel moth did not infest the redbuds last summer, but a year earlier a significant portion of the trees was defoliated in late summer.
At the time, I was unaware that the caterpillars were one of the stinging types until I stooped to pull a weed beneath a redbud’s arching branches. A few were dislodged from leaves onto my bare arm, and with the stinging parts facing up I was stung only when I flicked them off with my hand. This is not the first time I’ve been stung by caterpillars, and as I poke my nose too close, too often, it will certainly not be the last. The sting is painful enough that you will pay closer attention the next time.
I am interested to see if this webworm will be the same, but possibly it will be another caterpillar. In any case, I expect no long term damage to the redbuds. Though I do not spray pesticides, when I happen to notice an infestation I will closely watch it from start to finish. I read that a large portion of a bird’s diet is caterpillars, but I have yet to see it, and it seems this will not be a solution for the caterpillars. If the infestation becomes too severe, I can take action, but I don’t recall ever needing to do anything.
Several years ago, one of two weeping Golden Chain trees (Laburnum x watereri ‘Pendulum’, above) was infested with another stinging caterpillar. I watched over a week as the small tree was completely defoliated. I thought that I might have let this go too far, but the following spring there was no obvious loss of vigor, and with this experience I am curious to follow the progress of this year’s webworms.