After fellow new recruit Dominic Kerrigan scored on his debut in the 2-1 win over Atherton Collieries on Saturday, striker Howarth was on target in the Integro League Cup defeat to Bamber Bridge.
Howarth, 21, joins the EVO-STIK League West Division club from Ashton United, having previously played in the division for Skelmersdale United.
He came through the ranks at Blackburn Rovers, and starred for their Under 18s in 2015/16.
Defender Kerrigan was previously with Fleetwood.
Colne, who sit third in the table, host Trafford on Saturday.
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