En EspaŅol

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?

Share

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
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

QUESTION:

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.

ANSWER:

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 Pests Questions

Discouraging rattlesnakes in northern California
July 12, 2011 - Searching for information re: managing your garden to discourage snakes, especially rattlesnakes. I live in northern California and we have many. I found one of your articles, but the link to an U. of...
view the full question and answer

Something dripping from red oak in Austin
July 30, 2012 - There is a large red oak outside my apartment. The leaves are shiny and covered with what appears to be oil. The ground underneath is coated with this also. When I parked under the tree my car beca...
view the full question and answer

Problem with leaves of Texas Ash in Austin
May 21, 2012 - We purchased a 3' to 4' Texas Ash in March 2012. The past few days I noticed new leaves at the top are curled under, have a milky substance on them, and more than a few ladybugs on them. What is thi...
view the full question and answer

Treating cuts in tree trunks
November 21, 2009 - We have two young trees that deer made bad cuts in the trunks. What can we put on cuts to keep bugs and disease from getting in them.? Thank you.
view the full question and answer

Problems with Shumard Oaks and Crepe Myrtle in Cooke Co. TX
September 07, 2013 - I have a Shumard Oak Tree that has been in the ground approx. ten years. It has done great, even passing up some of my older Shumards. In August it began to lose its leaves at an alarming rate. They a...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center