| Chapter I. The Terebinth Aphids. | 4849 |
| Chapter II. Experiments | 4366 |
| Chapter III. Exchanging The Nests | 3236 |
| Chapter IV. More Enquiries Into Mason Bees | 6339 |
| Chapter V. The Story of My Cats | 4569 |
| Chapter VI. The Red Ants | 6205 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6278 |
| Chapter VIII. Parasites | 4100 |
| Chapter IX. The Theory of Parasitism | 4941 |
| Chapter X. The Tribulations of The Mason Bee | 5571 |
| Chapter XI. The Leucopses | 3304 |
