| Chapter I. The Terebinth Aphids. | 7367 |
| Chapter II. Experiments | 7393 |
| Chapter III. Exchanging The Nests | 5807 |
| Chapter IV. More Enquiries Into Mason Bees | 9298 |
| Chapter V. The Story of My Cats | 7054 |
| Chapter VI. The Red Ants | 11091 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8863 |
| Chapter VIII. Parasites | 6769 |
| Chapter IX. The Theory of Parasitism | 7460 |
| Chapter X. The Tribulations of The Mason Bee | 8419 |
| Chapter XI. The Leucopses | 5317 |
