The Banana Farmer doesn't believe in popping Bloons, but he's an expert when it comes to collecting bananas. Place him near your Banana Farms and he'll save you from the trouble of manually collecting the bananas.
More recently, on March 2016, the Monkey Farmer became a tower for Bloons Monkey City Mobile. It costs $1.99 USD for each Banana Barn and the Farmer itself is free to place when capturing tiles. Along with its original capability of collecting bananas and crates in-game, each Banana Barn building purchased provides a 10% increased capacity to each Banana Farm in the city, thus the effect can stack with other Barns. These do not appear in the Monkey Buildings tab until the Banana Farm Lab is built, provided that the player's City is at least Level 15.
On October 27th 2016, the Monkey Farmer became available on Bloons TD Battles Mobile as a one-use tower, and costs 200 each (formerly 100). It can be used only if the player chooses Banana Farms along the battle.
On December 19th 2018, Monkey Farmer now has a premium version of himself called Robo Farmer. Robo Farmer can collect all bananas from the entire screen, as well as attracting bananas towards him three times as fast. A set of 5 Robo Farmers cost $2.99 USD and will replace your Monkey Farmers when you pick a Banana Farm, until you use all of your Robo Farmers.
On March 14th 2019, Monkey Farmer returned as a premium Ally in Bloons Adventure Time TD. It keeps its purpose of collecting dropped items from the other BTD games. However, Monkey Farmer is a one time purchase of $2.99 USD to buy in the Store, and the monkey itself costs $200 to place, with infinite collect range. The Farmer's also the only ally to not have an upgrade tree as it doesn't attack or provide boosts to other characters in the game. Once bought from the store, you cannot have access to buy a second Farmer, but you can have multiple Farmers in game if you buy upgrades that increase quantities of said ally. He is equippable to any character, similar to the Business Men ally.
Oddly, even though it says that the Monkey Farmer is tired of picking up bananas, in its artwork he appears to be very happy (since he's being paid to do it; his salary does not affect your income, though).
It was released again in Bloons TD 5 Mobile because it is much harder to tap the bananas instead of moving your mouse on them and can be pretty risky because sometimes a tap might miss a banana and can spoil.
It may be efficient only if the given Specialty Building is a better choice in case of limited tower selection.
In Bloons Monkey City Mobile, if you have the Banana Replicator special item which increases the capacity of the player's first Farm by 150 in the city, placing a Banana Barn will give a 115 capacity increase to the first Farm instead of 100.
Although Farmers does not pop any Bloons, they do have a pop count in their tower interface.
Before the Robo Farmer update, Monkey Farmers used to cost 100 each instead of 200.