| Chapter I. The Terebinth Aphids. | 5187 |
| Chapter II. Experiments | 4743 |
| Chapter III. Exchanging The Nests | 3540 |
| Chapter IV. More Enquiries Into Mason Bees | 6700 |
| Chapter V. The Story of My Cats | 4914 |
| Chapter VI. The Red Ants | 6640 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6559 |
| Chapter VIII. Parasites | 4434 |
| Chapter IX. The Theory of Parasitism | 5485 |
| Chapter X. The Tribulations of The Mason Bee | 5950 |
| Chapter XI. The Leucopses | 3643 |
