Asked September 21, 2020, 6:24 PM EDT

Comment 1: I have been incessantly pulling out stilt grass, and still there is no resolution to this invasive grass. I know I can kill it, but will also damage or kill other perennial plants and shrubs as well, which I do not want to do. The Stilt grass is from my wood line...Athough our property, I cannot in good conscience destroy natural growth in the woods, I am still amazed that NO ONE had come up with a solution to eliminate this stilt grass without disturbing and distressing other plants, Comment 2: After I pulled out TON of stilt grass, I found the following underneath on the ground, I am hoping you can share what this might be? There were no insects flying around at all, and no ants seen at all...Just small mounds of upturned soil, some of which I stepped on to get to the rest of the stilt grass. I know you probabiy have no resolution to the stilt grass...but what about these little mounds of dirt ( approximately 1-2 inches in height, leading from our lawn toward our house. Can you identify these mounds? Need help!

Baltimore County Maryland

2 Responses

We sympathize with the frustrating invasion of Stiltgrass; it is very well-established in every county of Maryland, both in gardens and parks alike: Control measures are challenging because, like many invasive non-native weeds, there is no herbivore present here with consumes it, and in this case, its seeds are dispersed further by wildlife (mainly deer for Stiltgrass). Only a very host-specific herbivore (usually an insect) which attacks an invasive like Stiltgrass alone would have to be well-vetted to be harmless towards local species before being approved for release into the environment. (If such an insect exists, just because it consumes only Stiltgrass in its native habitat doesn't mean it will do so in ours.) Such targeted control attempts for other pests have backfired before, with the intended control agent instead consuming plants or pests outside of its intended use, becoming functionally useless for its intended task.

Invasive species are often better able to take advantage of damaged habitat more so than native plant colonizers, and this is why they can proliferate and spread so quickly once introduced - human-developed areas have lots of disturbed and degraded habitat, and can serve as "reserves" of invasive populations. The combination of habitat damage in conjunction with the over-population of deer exacerbates the problem - deer not only spread the seeds around but also eat native plants that might otherwise be competition for invaders.

Even though Stiltgrass is an annual and dies each winter, the seeds have long viability persistence and germinate so early that even when pre-emergent herbicide use is warranted, it often is applied too late for complete control. Similarly, herbicide use in wild lands is not always warranted due to impacts it may have on native flora, so control measures are limited to physical removal via hand-pulling, smothering (non-selective), repeated mowing (also non-selective and a risk to natives), goat browsing (again, too generalist, and usually they prefer broadleaf weeds and vines to grasses), or burning (here too, a generalist approach that harms natives too). Many of these measures are either cost-prohibitive for an organization or simply unsafe with regards to fire risk.

We cannot concretely identify the creator of the soil piles. They may be due to ants, and if you haven't seen any, it may be from a colony that has since died out. If they are in a line, then perhaps they are due to a tunneling animal like a mole, which can push-up soil from below without having an associated exit hole:


Thank you so much for your quick response.....I just thought by now, someone would have a definite recipe for the stilt grass issue.
,,,,,,,,I will check out the piles of dirt...yes leading in a line...since that is an area that was totally invaded by stilt grass. Hopefully, it is a deserted tunnel of whatever was there.

Very much appreciate this site and your responsiveness and help... Thank you again....Linda