The latex is a co-carcinogen and produces dermatitis in humans and livestock. Sheep graze spurge, particularly the young shoots, but the clones vary in palatability and spurge returns to its former density in two years of sheep removal. Tetraploid cypress spurge is a similar problem in eastern Canada where it is particularly dense on limestone and sandy soils. A stand at Arnprior, ON, apparently introduced from Britain in 1870, had spread to 14,000 ha by 1981. Native organisms have little impact on either spurge despite of attacks by the root-feeding fleabeetles Glyptina atriventis and G. brunnea.
Elk consume the young shoots and grasshoppers defoliate it in drought years.
However, the spurges displace most animals and plants including the threatened northern prairie skink and the endangered western prairie fringed orchid. The biocontrol of leafy spurge has been difficult. In this manual Canadian plants are called leafy spurge and the latin name is used for European plants. The difficulty of finding insects that thrive on leafy spurge is related to the latex in the plant, which is sticky and contains toxins that differ between populations. Some insect species specialized on E. virgata have done well on leafy spurge, but so have some from cypress spurge, from E. esula and other European spurges.