Iowa Code § 642.9: Failure to appear or answer — cause shown.

If, duly summoned, and the garnishee’s fees tendered when demanded, the garnishee fails to appear and answer the interrogatories propounded to the garnishee without sufficient excuse, the garnishee shall be presumed to be indebted to the defendant to the full amount of the plaintiff’s demand, but for a mere failure to appear no judgment shall be rendered against the garnishee until the garnishee has had an opportunity to show cause against the same.