Exotic grass invasion impacts fitness of an endangered prairie butterfly, Icaricia icarioides fenderi

  • Published source details Severns P.M. (2008) Exotic grass invasion impacts fitness of an endangered prairie butterfly, Icaricia icarioides fenderi. Journal of Insect Conservation, 12, 651-661.


This study is summarised as evidence for the following.

Action Category

Remove or control non-native or problematic plants

Action Link
Butterfly and Moth Conservation
  1. Remove or control non-native or problematic plants

    A replicated, randomized, paired, controlled study in 2004 in two upland prairies in Oregon, USA (Severns 2008) found that plots where non-native tall oat-grass Arrhenatherum elatius had been cut were used by Fender’s blue Icaricia icarioides fenderi more than uncut plots. In plots where oat-grass had been cut, Fender’s blue butterflies were more likely to bask (76–80% of 166 butterflies) or lay eggs (69% of 71 females) and less likely to fly straight over (17–24% of 166 butterflies) than in plots where oat-grass had not been cut (bask: 13–49% of 105 butterflies; lay eggs: 13% of 45 females; fly over: 47–87% of 105 butterflies). In cut plots, the density of eggs (2.5 eggs/leaf) was higher than in uncut plots (1.0 eggs/leaf). In May 2004, four pairs of plots (1-m radius, 2.5 m apart) were selected in each of two remnant prairies (1–5 ha). In one plot/pair, oat-grass was cut with shears to the same height as the native Kincaid’s lupine Lupinus sulphureus kincaidii leaves. In the remaining plots oat-grass was not cut. In May 2004, three pairs of plots/prairie were observed for 50 minutes, and butterflies flying over, basking, or laying eggs in each plot were recorded. In June 2004, all lupines within each plot were searched for eggs.

    (Summarised by: Andrew Bladon)

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