| Chapter I. The Terebinth Aphids. | 1849 |
| Chapter II. Experiments | 1632 |
| Chapter III. Exchanging The Nests | 1069 |
| Chapter IV. More Enquiries Into Mason Bees | 1964 |
| Chapter V. The Story of My Cats | 1755 |
| Chapter VI. The Red Ants | 1540 |
| Chapter VII. Some Reflections Upon Insect Psychology | 2982 |
| Chapter VIII. Parasites | 1218 |
| Chapter IX. The Theory of Parasitism | 1317 |
| Chapter X. The Tribulations of The Mason Bee | 1972 |
| Chapter XI. The Leucopses | 789 |
