Some people don't really like Pelargoniums, but I think I'm a fan out of nostalgia; my grandparents always grew them in a pot on their patio, next to a statue of St. Francis. They are pretty drought tolerant and they were really easy to grow from seed, so I'm not giving up on them.
However, I may have to -- I went to check on them in the basement, to see if they were alive or needed water. To my dismay, they were clearly being eaten. There were little holes in the leaves, or sometimes entire leaves eaten to the stem. On closer scrutiny, I was thoroughly grossed out to discover little green worms were the culprits. Some were tiny, others were more than an inch long. I picked off as many as I could find, and went about researching if my plants were goners.
After some googling, my suspicion is that the worms are cabbage loopers. I did buy some Dipel Dust (an organic bacterial insecticide, which kills the worms), and I'm hoping it will do the trick. It's possible I have Tobacco Budworm, a common Pelargonium/Geranium pest, but the worms weren't reddish or brownish, and the Dipel might work on them too.
Wish me Luck!
P.S. Why is there so much confusion over Geranium's? If I refer to them as Pelargoniums, no one has any idea what I'm talking about, but Geranium is actually the scientific name for a Cranesbill. Which are much more rare (though awesome)...
Photo credit: Extension Entomology, Texas A&M University