| Chapter I. The Terebinth Aphids. | 5010 |
| Chapter II. Experiments | 4536 |
| Chapter III. Exchanging The Nests | 3383 |
| Chapter IV. More Enquiries Into Mason Bees | 6519 |
| Chapter V. The Story of My Cats | 4744 |
| Chapter VI. The Red Ants | 6409 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6426 |
| Chapter VIII. Parasites | 4270 |
| Chapter IX. The Theory of Parasitism | 5262 |
| Chapter X. The Tribulations of The Mason Bee | 5748 |
| Chapter XI. The Leucopses | 3508 |
