A reader wrote to us recently to ask “what kind of worm falls from the sky?” (The reader actually added three question marks, perhaps indicating his level of concern.) It turns out that the worms, which are small and white, aren’t actually falling from the sky, but rather from an oak tree (or so we surmise – more on this in a moment). The small white worms fall onto our reader’s car and truck, which are parked under an oak tree. The reader was first of all concerned with identifying what the small white worms on the oak tree are, but he was also keen to know where they are coming from. We address both concerns below.