With the spring and onset of summer comes the return of the lerp psyllid insect to Rancho Santa Fe’s trees, an insect that eats up red gum eucalyptus foliage and leaves behind a big mess. The weather being cold and rainy for the last two winters has helped—the lerp psyllid population dies down in the cold months and that, in combination with the abundant rain, has reduced the overall stress on the trees, they are able to sustain themselves a bit better, said Caitlin Kreutz, RSF Association Parks and Recreation assistant manager. But with the return of warmer weather, the lerps are back.