Have used worm castings in Spring for several years. Concerned now because I’ve read they do contain worm eggs. With jumping worms and many native plants that do not benefit from worms in the soil I am now wondering if is a good idea t continue using the castings.
Your question is a good one and very timely. I feel like I have been hearing a lot about this unwanted visitor and it is important to know what we can do to prevent its spread. There are actually three species of concern: the rustic jumping worm, Amynthas agrestis, the compact jumping worm, Amynthas tokioensis, and the large jumping worm, Metaphire hilgendorfi. They were introduced from Asia, mainly from Japan.
There is not yet a lot of information available about whether or not it is safe to use worm castings specifically. According to the Invasive Species Centre here in Canada, invasive jumping worms are transported here primarily through horticulture. They emphasize the importance of avoiding buying mulch, compost, nursery stocks, or potting mixes from areas with established jumping worm infestations, as these may contain egg-filled cocoons which are difficult to distinguish from the surrounding soil or debris. Last year there was an increase in reports of jumping worms here in Toronto, so we definitely should be on the look out.
One thing you can do is ask your garden/castings supplier where their source is coming from. If purchasing soil and mulch, ask for brands that are heat-treated as jumping worms and their cocoons cannot survive temperatures above 40C for 3 days. If you are still unsure, you could reduce the risk of bringing in contaminated materials simply by using your own compost.
I hope this helps you make a decision.