Lettuce not sure I can explain this well

We are growing lettuce both at home and on the lottie but the lettuce at home are fine, the ones at the lottie are becoming a mystery.

Yesterday I went up and one of the red ;ettuce looked really limp, strange as all the others were fine, I went over and thought maybe it needs a drink or a slug is eating it from beneath, I lifted the leaf slight;y to look under and the whole thing lifted in one, it had been taken off at the root, ground level and left in place.

No sign of slug trail or other hungry bugs.

hubby and I are on different fences with this, he says its been cut off and placed back down on the soil, I say bug but what i dont know. Its annoying as the bug didnt eat it, what a waste.

anyone had anything similiar. Bug or angry plotter who doesnt like my lettuce 

i had same problem with a few of my radish not sure wot did it tho sorry

Many years ago on the farm we used to have occasional problems with caterpillars eating the roots of our lettuces. I have no idea what moth or butterfly they turned into but the symptoms were just as you describe - a floppy looking lettuce and on further investigation a grub not far from the root.

And they used to get a good squishing

Poop I did find a dead caterpillar looking thing, more black beside the first one, it was dead already, so I didnt need to do the deed myself 

Put cutworms and caterpillars and other plant harming bugs in a short glass or plastic container, like wot supermarket puddings come in. Then put them in an accessible place. The birds (esp robins) will get a good meal from that. No squashing required.

I put them in a flower pot drainer saucer thing - do the same to ants eggs. The robin(s) and blackbirds love them. Just saves the birds digging them up, I say
Oliver