En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer
5 ratings

Wednesday - January 03, 2007

From: Austin, TX
Region: Southwest
Topic: Non-Natives, Compost and Mulch, Pests
Title: Possible damage by invasive, non-native earthworms in compost
Answered by: Nan Hampton


I received a worm bin (vermicomposter) for Christmas. The instructions that came with the bin say to use the red wiggler worm (Eisenia foetida) and that it is okay if some of the worms go into your garden with the compost that you harvest. I have heard that there are some invasive worm species in different parts of the world that make quick work of the valuable leaf cover in forests. I live in Austin, Tx and want to know if it is really okay if some of my worms go into the garden.


You are correct that there is concern about the ecological impact of exotic earthworm species in North America. Eisenia fetida is an import from Europe. Nick Proulx of the Minnesota Department of Natural Resources discusses the problem in Ecological Risk Assessment of Non-indigenous Earthworm Species. The major concern for exotic earthworms is for recently glaciated regions of the United States where native earthworms are lacking. In these northern deciduous forests the earthworms feed on the leaf litter and the concern is that these exotic earthworms cycle the leaf litter so quickly that it affects the soil's structure. This can result in far-ranging effects on many native plants and animals. For unglaciated regions of North America where there are native earthworm species, the main concern is that the exotic species will out compete the native species. One study in Kentucky showed native species occurring in undisturbed forest areas and exotic species occurring in disturbed areas. The bottom line is that in the far northern deciduous forests there is great concern over the presence of exotic species of earthworms because of their effect on the soils; while in the unglaciated southern regions, although there is some concern, the impact of the exotic species on soil processes is of minimal concern.

The study on the effects of exotic invasive earthworm species is ongoing—see the 2006 article Invasion of Exotic Earthworms into Ecosystems Inhabited by Native Earthworms by P. F. Hendrix et al. in Biological Invasions, Volume 8, pp. 1267-1800. The paper concludes (given limited data) that exotic earthworms do invade areas occupied by native species and this can occur even if there is no obvious disturbance. Sometimes the natives dominate and sometimes it is the exotics. In cases where the exotics are predominant, it may be because that they are able to use resources that the natives can't use. It is still uncertain as to how serious a threat the exotic species are to native species in the unglaciated regions.

The habitat and available food will define where exotic species can live. Eisenia fetida lives in surface soil and its food is leaf litter, microbes, and soil with high organic content. Hendrix and Bohlen (Hendrix, P. F. and P. J. Bohlen. 2002. Exotic Earthworm Invasions in North America: Ecological and Policy Implications. BioScience V. 52, no. 9, pp. 801-811) say: "Earthworms species from northern latitudes (e.g., European lumbricids and some Asian megascolecids) are poor colonizers in tropical or subtropical climates (except in localized temperate situations), and vice versa. For example, despite continued and widespread introduction throughout the United States, Eisenia fetida, the lumbricid 'manure worm' commonly used in vermicomposting, is not often found in natural habitats in the southern United States." So, unless your worm bin is situated in an area with lots of leaf litter and/or soil high in organic matter, any escapees from the bin should not be a serious problem. You can read more about the biology of Eisenia fetida The Science of Composting (from Cornell University).


More Compost and Mulch Questions

Native grass lawn for San Antonio
June 25, 2011 - Dear Mr Smartyplants, I live outside of San Antonio and my question is in regards to putting in a native grass lawn. What type of soil should I put down? I've sprayed herbicide and was planning on ...
view the full question and answer

Sudden death of Texas Mountain Laurel
April 14, 2008 - Last year, my 15-year-old Mountain Laurel died very suddenly. The leaves began to curl up and turn brown, and it was dead within about 15 days. What happened?
view the full question and answer

Yellow leaves on non-native pittisporum in Wharton TX
March 17, 2009 - Green pittisporum that I planted 2 years ago and 1 year ago are getting a lot of yellow leaves. Variegated pittisporum that I planted at the same 2 times are doing fine.
view the full question and answer

Too late to begin planting in May in Austin?
April 30, 2008 - Is it too late to begin planting in May? I live in Austin Texas and have finally completed my plans for a native Texas landscaping (plants and grass) of my front yard. I'd like to get the landscapi...
view the full question and answer

Century plants spread through offshots from Rye TX
September 20, 2010 - How do century plants spread? Are the little ones the babies?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center