| Chapter I. The Terebinth Aphids. | 6367 |
| Chapter II. Experiments | 6045 |
| Chapter III. Exchanging The Nests | 4595 |
| Chapter IV. More Enquiries Into Mason Bees | 7939 |
| Chapter V. The Story of My Cats | 6106 |
| Chapter VI. The Red Ants | 8994 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7724 |
| Chapter VIII. Parasites | 5643 |
| Chapter IX. The Theory of Parasitism | 6529 |
| Chapter X. The Tribulations of The Mason Bee | 7289 |
| Chapter XI. The Leucopses | 4539 |
