Jerry hit -- is an important part of the Rollins leadership team and his in-depth knowledge of our business and experience gained from working in our industry since 1991 adds perspective.
As a recent example, we're pleased to share that Rollins made an in-kind donation originally costing $4.6 million dollars worth of personal protective equipment or PPE items during the third quarter.
Working with the Federal Emergency Management Agency and several philanthropic organizations including the Friends of Disabled Adults and Children, the Foundation of HOPE Food Bank, as well as COPE Preparedness in Los Angeles, we donated 27 pallets or 6.8 million pieces of masks, gloves and other items.
In accordance with accounting standard ASC 450, we have established a reserve related to this matter which we consider immaterial.
Revenue increased 11.4% to $650.2 million compared to $583.7 million for the third quarter of last year.
Our net income totaled $93.9 million or $0.19 per diluted share compared to $79.6 million or $0.16 per diluted share for the same period in 2020.
Revenues for the first nine months of 2021 were $1.824 billion, an increase of 12.2% compared to $1.625 billion for the same period last year.
Net income for the first nine months increased 44% to $285.3 million or $0.58 per diluted share compared to $198.2 million or $0.40 per diluted share for the comparable period last year.
For the quarter, we experienced solid growth in all our business lines with residential increasing 11.7% and termite presenting percent growth over the third quarter 2020.
Additionally, commercial excluding fumigation delivered an impressive 10.1% growth over the third quarter last year.
This is also an improvement of 7.9% growth over two years ago when we were not experiencing COVID related shutdowns.
Since 2010, the business has grown 800%.
There are currently 84 franchises with the most recent franchise launching in Mansfield Ohio.
We anticipate finishing the year with 12 new franchises, one of our strongest years in adding franchisees.
Through the Rollins Employee Relief Fund, we granted 137 emergency grants to impacted employees within the first week following the hurricane to enable employees to address their personal essential needs.
Think about this, over the last three years we have averaged 30 acquisitions per year.
Our third quarter revenues of $650.2 million was an increase of 11.4% over last year.
Of the 11.4% actual exchange rate revenue growth, acquisition growth was 2.2%, and organic equated to 9.2%.
For the nine months ended September 2021, revenue of $1.824 billion was an increase of 12.12 percentage over year-to-date 2020.
Of this actual exchange rate total revenue growth of 2.
-- or excuse me, of 12.2%, 2.7% was related to acquisitions, and 9.5% organic growth.
The constant year-to-date exchange rate total revenue growth for 2021 equaled 11.6%; 2.7% represented acquisitions and 8.9% organic revenue growth.
For the third quarter in 2021, wildlife revenues grew 24.1% over last year, and year-to-date wildlife has presented an overall revenue growth of 27.6%.
What makes us particularly impressive at this is that this is after their strong growth of 20.4% last year.
So, third quarter 2021 EBITDA was $150.9 million or 8.7% over 2020 third quarter adjusted EBITDA of $138.9 million.
Third quarter 2021 earnings per share was $0.19 per diluted share or 5.6% improvement over the 2020 third quarter adjusted EPS.
For the nine months ended September 2021, our adjusted EBITDA was $422 million or 22.1% over last year's adjusted EBITDA of $344.9 million.
Year-to-date 2021 adjusted earnings per share was $0.53 per diluted share or 26.2% over last year.
For the third quarter 2021, gross margin increased to 53% or 0.4% over last year.
Strong improvements in our materials and supplies were negatively offset by high overall fleet costs primarily from an increase in fuel of approximately $4 million over third quarter 2020, and lower vehicle gains of $900,000 compared to last year.
Travel expenses have also increased $1.3 million in the third quarter as we have begun to lift our company travel restrictions.
Amortization expenses for the third quarter 2021 increased $1.4 million due to the amortization of customer contracts from multiple acquisitions.
This was offset by a decrease in depreciation of $201,000 due to the sale of owned vehicles and centralizing of IT function.
Overall, this equated to a 5.1% increase in depreciation and amortization over the third quarter 2020.
Our dividends paid year-to-date 2021 was $119.7 million or an increase of 30.4% over last year.
We ended the current period with $117.7 million in cash, of which $73.6 million was held by our foreign subsidiaries.
For the third quarter of 2021, our free cash flow is $72.9 million or a decrease of 27.5% over the same quarter last year.
For the nine months ended 2021, our free cash flow equal $278.9 million or 13.6% decrease over year-to-date 2020.
This fluctuation occurred due to the deferral of $30.3 million in FICA taxes payable in 2020 as allowed under the CARES Act.
Lastly, I want to discuss that yesterday we were extremely pleased to announce that our Board has approved a 25% increase to our dividends.
The quarterly dividend increased to $0.10 per share from $0.08 per share and will be paid on December 10, 2021 to stockholders of record at the close of business on November 10, 2021.
Additionally, the Board also approved a special dividend of $0.08 to be paid on December 10, 2021 as well.

Summary:
Revenue increased 11.4% to $650.2 million compared to $583.7 million for the third quarter of last year.
Our net income totaled $93.9 million or $0.19 per diluted share compared to $79.6 million or $0.16 per diluted share for the same period in 2020.
Our third quarter revenues of $650.2 million was an increase of 11.4% over last year.
Third quarter 2021 earnings per share was $0.19 per diluted share or 5.6% improvement over the 2020 third quarter adjusted EPS.