Glyn Webster has been reading How I Found Livingstone by Henry M Stanley, and sends this splendid extract:

Mpwapwa, though the traveller from the coast will feel grateful for the milk it furnished after being so long deprived of it, will be kept in mind as a most remarkable place for earwigs. In my tent they might be counted by thousands; in my slung cot they were by hundreds; on my clothes they were by fifties; on my neck and head they were by scores. The several plagues of locusts, fleas, and lice sink into utter insignificance compared with this fearful one of earwigs. It is true they did not bite, and they did not irritate the cuticle, but what their presence and numbers suggested was something so horrible that it drove one nearly insane to think of it. Who will come to East Africa without reading the experiences of Burton and Speke? Who is he that having read them will not remember with horror the dreadful account given by Speke of his encounters with these pests? My intense nervous watchfulness alone, I believe, saved me from a like calamity.

Mr Webster adds:

I haven’t been able to learn more! Not of Burton and Speke’s earwig experiences nor the nature of unnamed horror a plague of earwigs implies.

I am going to embark on further research myself, but in the meantime if any reader knows what Stanley is getting all worked up about please leave a note in the Comments.