Section 15. Each local superintendent shall render to the chief superintendent not later than the twenty-fifth day of each month a certified itemized statement of his expenditures during the preceding month, with vouchers showing separately the amounts expended on public lands and private lands for the suppression and control of the public nuisances named in section eleven, other than the Dutch elm disease and the beetles which spread said disease, and a similar statement of expenditures on Dutch elm disease control and the removal and destruction of elm trees then infected with the disease or infested with the beetles which spread the disease, and wood which was then or was likely to become a breeding place for said beetles.