| Chapter I. The Terebinth Aphids. | 5959 |
| Chapter II. Experiments | 5606 |
| Chapter III. Exchanging The Nests | 4205 |
| Chapter IV. More Enquiries Into Mason Bees | 7505 |
| Chapter V. The Story of My Cats | 5688 |
| Chapter VI. The Red Ants | 8234 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7319 |
| Chapter VIII. Parasites | 5258 |
| Chapter IX. The Theory of Parasitism | 6135 |
| Chapter X. The Tribulations of The Mason Bee | 6810 |
| Chapter XI. The Leucopses | 4213 |
