| Chapter I. The Terebinth Aphids. | 7390 |
| Chapter II. Experiments | 7457 |
| Chapter III. Exchanging The Nests | 5836 |
| Chapter IV. More Enquiries Into Mason Bees | 9315 |
| Chapter V. The Story of My Cats | 7074 |
| Chapter VI. The Red Ants | 11177 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8886 |
| Chapter VIII. Parasites | 6806 |
| Chapter IX. The Theory of Parasitism | 7481 |
| Chapter X. The Tribulations of The Mason Bee | 8441 |
| Chapter XI. The Leucopses | 5327 |
