| Chapter I. The Terebinth Aphids. | 6287 |
| Chapter II. Experiments | 5966 |
| Chapter III. Exchanging The Nests | 4529 |
| Chapter IV. More Enquiries Into Mason Bees | 7865 |
| Chapter V. The Story of My Cats | 6049 |
| Chapter VI. The Red Ants | 8891 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7664 |
| Chapter VIII. Parasites | 5573 |
| Chapter IX. The Theory of Parasitism | 6462 |
| Chapter X. The Tribulations of The Mason Bee | 7259 |
| Chapter XI. The Leucopses | 4497 |
