Insect Frass

What is insect frass and how does OMRI review it?

By Tara Sistrunk

Insect frass is debris or excrement from larvae and mature insects. Similar to the production of worm castings, frass is produced by introducing larvae or mature insects to feedstocks such as food scraps or grains, and then allowing them to grow. Larvae or mature insects are then separated from their excrement, which is collected and sold as a fertilizer. The frass can be applied directly to the soil, added as an amendment to potting mix, made into a water extract, used as a foliar feed, or added to hydroponic systems. Frass can contain beneficial bacteria, amoebas and fungi, and provides plant-available chitin. 

OMRI has standards for reviewing frass to the National Organic Program (NOP). Under NOP standards, frass produced using allowed, non-manure feedstocks, and that does not contain more than 1x10³ (1,000) MPN fecal coliform per gram sampled, or more than 3 MPN Salmonella per 4 grams sampled, is considered to be “Allowed,” and can be applied at any time during the growing season. Frass produced using manure feedstocks will be listed as “Allowed with Restrictions” and carries the same restrictions as raw manure outlined at §205.203(c)(1). 

Regarding the Canada Organic Regime (COR) standards, the Permitted Substances List (PSL) at CAN/CGSB 32.311 Table 4.2, Soil Amendments and Crop Nutrition, previously included an entry for “Humus from worms and insects (vermicompost),” which referenced the entry for “Worm castings,” also on Table 4.2. However, Humus from worms and insects (vermicompost) was removed from the PSL in the 2020 COR standards update. In 2022, the Canada Standards Interpretation Committee (SIC) clarified that frass from insects should not be reviewed as per the PSL Table 4.2 Worm castings entry. Rather, insect frass should be considered the same as animal manure, and is required to be from organic insects if commercially available. The SIC also noted that insect frass should either be applied according to the days-to-harvest restriction per CAN/CGSB 32.310 5.5.2, or processed as outlined in 5.5.3 for processed animal manure. Insect frass is also a permitted compost feedstock. 

OMRI has updated its review policies for insect frass according to these clarifications of the COR regulations. 

This article was originally published in the winter 2016 edition of the OMRI Materials Review newsletter, and was revised and updated in March 2023 by Senior Bilingual Technical Coordinator Tina Jensen Augustine.