All other actions for recovery of a debt provable in bankruptcy or insolvency, when it appears that any defendant therein has filed his petition in bankruptcy or insolvency or has been adjudged a bankrupt or an insolvent, on petition of his creditors before or after the commencement of the action, shall be continued until the bankrupt or insolvent proceedings are closed unless the plaintiff strikes such defendant's name from the action, which he may do without costs; but when such defendant does not use diligence in the prosecution of his bankrupt or insolvent proceedings, after 30 days' notice to him in writing from the plaintiff, the court may refuse further delay.