Gary: Caterpillars are happy with the rain? All good or all flood at your place?
All good Frank. In anticipation of El Niño I installed a rain gutter system. The yard is on a bit of a grade, a retaining wall in the very back, a three foot drop, then a downward slope to the front. Until this year the patio would flood and the areas near the house would swamp. With the rain gutters and barrels I have significantly reduced the flooding and swamping. I have repeatedly emptied the rain barrel water into the koi pond, potted plants and flower beds. (I have an extensive potted veggie garden all cosy in pots ranging from 1.5' to tree size pots.) I have discovered the need for larger rain barrels.
The caterpillars tend not to feed during the rain. The above caterpillar is a Monarch. We have caterpillars and butterflies all year long. Monarchs, Whites, Sulphurs, Painted Ladies, Morning Cloaks and Swallow Tails are the most common. We've choose many plants based upon butterfly and hummingbird attraction. (We have hummers all year long also.) Often, the Monarch caterpillars will completely strip a Milkweed plant and we have to round-up and move the caterpillars to different Milkweeds.
This was the first El Niño storm to hit Southern California ... Apparently many more are stacked up and making their way across the Pacific. The problem with California rain is the heavens open up and dump everything at once. It doesn't rain very often in Southern California, but when it does it isn't gentle. Combine a heavy rain with a steep terrain (local mountain are approx. 10,000' high), barren foothills (massive bushfires burned all the hillside vegetation) and you have a formula for flooding and mudslides on a Biblical proportion. The flood control channels and rivers are wild and peaking with exploding, brown choppy/churning water. The Los Angeles River is largely concrete and at it's peak was designed to move 146,000 cubic feet of water every second. The Colorado River, sculptor of the Grand Canyon, can't do a quarter of that. California receives about 25% of the annual rainfall of France, but we have twice the amount of flood control.
After four years of drought, this is a good thing, but be careful for what you wish for.