When Julia and I first moved here in August, our front yard looked like this:
Some people might not see anything wrong with this picture, but to me the only thing worse than a neatly mown lawn would be if the whole place was covered with pavement. By this time next year, this area will be full of fruit trees and a vegetable garden, but in the meantime we’re enjoying seeing what plants spring up in the absence of a lawnmower. For the most part, the grass has stayed pretty short, but here and there some wildflowers have grown to heights of two feet or so. Near the middle of the lawn is this little clump of daisy fleabane (Erigeron annuus):
Just to illustrate the effect on local biodiversity of allowing a single individual of a native wildflower species to grow in your yard, here are three different leaf mines I found on this one plant a few weeks ago:
The above leaf has mines of two agromyzid fly larvae, one of which is still present (the yellow blob near the right end of the lower mine). Erigeron hosts a dozen or so agromyzid species and I’m not sure yet which one this is.
This puffy yellowish blotch is made by a moth, Parectopa plantaginisella (Gracillariidae). Incidentally, V. T. Chambers named this moth Gracilaria plantaginisella in 1872 after the genus of plantain (Plantago) because he thought that was the host plant at the time, but in 1877 he tried to rename it G. erigeronella, having realized that the true host was Erigeron. He wrote, “It is not necessary to explain how I was led into the error of supposing that this species feeds on Plantago instead of Erigeron.” I suspect that he originally mistook the broad leaves in a basal rosette of an Erigeron for plantain and didn’t want to admit it. Plantain continues to be erroneously reported as a host plant for this species, and the recent Peterson moth guide has compounded this error by giving fleabane and plantain as the hosts for Parectopa robiniella, which actually mines in black locust leaves. But I digress.
The above leaf contains a third type of mine, and is backlit to show the moth larva inside as well as the complete absence of excrement (“frass”) in the mine. The explanation for this is in the photo below, taken the following day after I had collected the leaf in a vial:
The fastidious caterpillar returns to the beginning of its mine between meals and deposits its droppings in a pile on the leaf surface. I believe this leaf mine is unknown to science, whether or not the adult moth has a name, but I suspect it is one of the “twirler moths” (Gelechiidae). Unfortunately I’ve only found one of these mines so far, and I’m not sure if the larva still alive, but I’ll certainly look for more next year.
Over the past few days, several adult flies have emerged from mines like the ones in the first photo.
Also over the past few days, eight adults of Parectopa plantaginisella have emerged from leaves I collected.
They are gorgeous creatures, and since I already knew what they were, I was happy to be able to release them unharmed back to their natal daisy fleabane plant this morning after I’d taken some pictures. Like many gracillariids, their long antennae were constantly whirling about even though most of them otherwise held still long enough for me to get some good shots.
In the same vial as the moths, two of these pale, delicate midges emerged, just over a millimeter long:
I’m not sure exactly what they are yet or how they got there. Although this fleabane had galls of Asteromyia modesta on some of its leaves, these clearly do not belong to that species, which I’ve accidentally reared previously from a goldenrod leaf.
There are also, of course, many other insects using this plant, including various bees and flies visiting the flowers, but I figure that any plant that is hosting three different leafminers is already earning its keep around here.