diff --git a/src/modules/butterflies/butterflies_populations.c b/src/modules/butterflies/butterflies_populations.c
index 1ce531422f0946aa649381543248976f8856bf92..03f842cb3315be0c1bc4c25975729b796e79f1d0 100644
--- a/src/modules/butterflies/butterflies_populations.c
+++ b/src/modules/butterflies/butterflies_populations.c
@@ -18,16 +18,17 @@
 int64_t count_populated_cells(const struct cats_grid *grid)
 {
         int64_t cells = 0;
-        cats_dt_coord rows = grid->dimension.rows;
-        cats_dt_coord cols = grid->dimension.cols;
+        const cats_dt_coord rows = grid->dimension.rows;
+        const cats_dt_coord cols = grid->dimension.cols;
+
         for (cats_dt_coord row = 0; row < rows; row++) {
                 for (cats_dt_coord col = 0; col < cols; col++) {
                         if (get_adult_population(grid, row, col)) {
                                 cells += 1;
                         }
-
                 }
         }
+
         return cells;
 }
 
@@ -35,22 +36,23 @@ int64_t count_populated_cells(const struct cats_grid *grid)
 int64_t butterflies_prune_invalid_cells(struct cats_grid *grid)
 {
         int64_t invalid_habitat = 0;
-        int module_id = CATS_MODULE_ID;
-        struct grid_data_butterflies *data = grid->grid_modules[module_id].module_data;
-        cats_dt_coord rows = grid->dimension.rows;
-        cats_dt_coord cols = grid->dimension.cols;
+        const int module_id = CATS_MODULE_ID;
+        const struct grid_data_butterflies *data = grid->grid_modules[module_id].module_data;
+        const cats_dt_coord rows = grid->dimension.rows;
+        const cats_dt_coord cols = grid->dimension.cols;
 
         for (cats_dt_coord row = 0; row < rows; row++) {
                 for (cats_dt_coord col = 0; col < cols; col++) {
+
                         if (!(data->info_layer[row][col] & BF_CELL_VALID_DISPERSAL_TARGET)) {
                                 if(get_adult_population(grid, row, col)) {
                                         invalid_habitat += 1;
                                 }
                                 set_population_ignore_cc(grid, row, col, 0);
-
                         }
                 }
         }
+
         return invalid_habitat;
 }
 
@@ -83,12 +85,9 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         }
 
 
-
-
-
-        // the number of generations per cell is usually not an integer value
+        // The number of generations per cell is usually not an integer value:
         // the non-integer part of the number of generations is used in the generation which is
-        // one greater than the integer part of the number of generations
+        // one greater than the integer part of the number of generations.
         // i.e. if the number of generations is 2.4, 40% of all eggs in the cell
         // will be considered as if they belonged to generation 3
         // the minimum number of generations is 1 if the cell is climatically viable (and the host species is present)
@@ -117,7 +116,7 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         assert(this_generation_fraction <= 1.0);
 
         //cats_dt_population max_cc = (cats_dt_population) grid->param.carrying_capacity.max_rate;
-        float eggs = this_generation_fraction * data->eggs[row][col];
+        const float eggs = this_generation_fraction * data->eggs[row][col];
 #ifdef BF_DEBUG
         printf("BFDBG::%s::row %d, col %d: local gen %f gen fraction %f, eggs %f, this gen eggs %f\n",
                __func__, row, col, local_generation, this_generation_fraction, data->eggs[row][col], eggs);
@@ -133,7 +132,6 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         data->eggs[row][col] -= eggs;
         assert(data->eggs[row][col] >= 0);
 
-
         // not capped, we can have more adults than CC
 
         cats_dt_environment suit = get_suitability(grid, row, col);