Ladybirds in the Thistle

The "crop" of bull thistle on our Littleton, Colorado farm is exceptional this year, no doubt fueled by the wet spring.  While guide books and websites suggest that this thorny wildflower may grow to 6 feet in height, we have one stand that exceeds 8 feet.

Considered a weed by most suburbanites and ranchers, bull thistle does attract a wide variety of wildlife.  The numerous pink-purple flowers are magnets for bees, butterflies and hummingbirds while the abundant seeds are eaten by finches, field mice and meadow voles; even the spiny foliage is consumed by deer and cottontails.  Of special interest this year is a large number of ladybird beetles in one of the thistle stands; close observation revealed colonies of aphids and scale insects that have attracted these predatory beetles.  I also observed tiny clusters of yellow eggs on the leaves; voracious ladybird larvae will hatch from these eggs, feast on the invasive insects, molt several times and then pupate before emerging as adults.

Here is a case where a maligned "weed" is hosting a large colony of beloved beetles that will go on to protect many other plants on our farm.  The diversity of plants and animals in a landscape, however small, is perhaps the best sign of its health.  Using herbicides to eliminate "weeds" diminishes that diversity and introduces toxins that, no doubt, threaten the welfare of all life forms in the ecosystem.