"I'm scared of them. What if they get me?"

"They're not going to get you," I said, drawing the blankets up beneath the youngest daughter's chin. Smoothing the covers with my hand, I took care to tuck her feet in so that she was wrapped up like a human calzone, as she likes.

"But they might get me."

"Sweetie, it's too dry in here. Leeches don't like the dry. They like wet, dark swampy water."

"But can I have some socks just in case?"

It was way past bedtime, and like many a parent before me, I was trying to maintain outward cool while inwardly panicking that it was taking so long to get everyone brushed and washed and tucked in. Every minute past 9 o'clock -- I know, I know, it was late for a school night -- is another nail in the coffin of a successful next day, if you don't mind a total scramble of metaphors.

"You really do not need socks," I said as tenderly and implacably as possible.

We were running late because a certain weak-willed parent had relented every time her audience begged, "Another chapter, please!" We're on our family's fourth run through the Laura Ingalls Wilder oeuvre, a cycle that started 15 years ago, and had just got to the bit in "On the Banks of Plum Creek" in which Laura and Mary go splashing in the creek. There they discover not only the crab that will persecute the odious Nellie Oleson in a later chapter (to everyone's satisfaction but hers), but also the muddy, boneless horrors that haunt shady parts of still water.

Leeches do not just haunt water. They also lurk in the childish imagination, as I knew from experience.

I remember standing on the end of a pier with my father when I was about 6. My father was pointing: Did I see the leeches? I looked and looked, but all I saw were wavy lines of sand in water made green by sunlight. Look closer, he said. Don't you see them now? I looked closer, and I still didn't see, but I wanted to please him. Oh, now I do, I said. Maybe those long green ropy things weren't ripples in the sand, but leeches! If so, then leeches were the length of a man's arm and as thick as sausages! At that moment, a cold terror of leeches settled in my mind, and leeches began oozing regularly through my nightmares.

Six or seven years later, I spent a lovely afternoon with a friend, messing around with makeshift floats in a farm pond in Maine. Our legs dangling in the water, we propelled ourselves around using wooden shingles as paddles. At dusk, we got out of the water, and I bent to brush the lumps of mud off my legs -- just as Laura Ingalls had done a hundred years earlier.

The mud didn't come off. In a horrified flash I saw what the lumps really were. I am not sure exactly what happened next, because a miasma fell over my eyes and someone started screaming, and when I came to my senses, trembling, dirt and blood were smeared all over my legs, and a lot of very squished brown leeches were strewn on the ground. My friend was gazing at me, open-mouthed.

Snapping out of the memory, I looked at the small worried girl in her bed.

"I don't know what I was thinking," I said to her, going to the sock drawer. "Of course you can wear socks in case of leeches."

"Oh, thank you, Mummy," she said, with real relief. "I mean, I know they can't actually get me. But tonight I want to be all covered up. Just in case."

Meghan Cox Gurdon's column appears on Sunday and Thursday. She can be contacted at mgurdon@washingtonexaminer.com.