Coffee Grounds attracting woodlice in the compost bin

As part of National Allotment Week, we have involved children in a Compost Safari hunting for creatures in the compost bins on our Demonstration site at Stokes wood.

One of the partially filled   bins had been left with coffee as the top layer for 5 days when I run out of time when layering it having reached about threequarters capacity. The bin was covered with plastic  sheet until the next layer could be added. When checking this bin, which had about  50% moisture content, we found masses of woodlice in the coffee layer.  There were not excessive amounts elsewhere in the bin, giving the impression  that they had been attracted to the coffee. Distribution was normal in adjacent bins without coffee.

I am not concerned at the presence of woodlice as the first time the bin is turned the coffee layer will be distributed throughout the bin and the woodlice will return to  their usual distribution in the organic material.

However, I can find no reference to woodlice being attracted to coffee has anyone experience of coffee drinking woodlice ?