President Rodrigo Duterte's unpredictable speeches frequently contain bombshell pronouncements, but the surprise this time came in the form of a cockroach that landed and ambled down the leader's shoulder.

The bug popped up on Duterte as he was extolling the virtues of the candidates he has endorsed for next week's midterm polls at a campaign rally late Wednesday.

An aide tried but failed to scrape the critter away with a bundle of papers she was holding, but Duterte brushed it aside as the government broadcast cut to a smiling but bemused audience in Bohol.

Duterte, who was nearing the end of his roughly 90-minute address, joked that the insect belongs to the opposition party.

Duterte is on the campaign trail to rally support for his candidates in next week's midterm polls, in which some 18,000 seats ranging from local councils to the upper house Senate are up for grabs.