| Chapter I. The Terebinth Aphids. | 7014 |
| Chapter II. Experiments | 6941 |
| Chapter III. Exchanging The Nests | 5392 |
| Chapter IV. More Enquiries Into Mason Bees | 8825 |
| Chapter V. The Story of My Cats | 6745 |
| Chapter VI. The Red Ants | 10123 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8488 |
| Chapter VIII. Parasites | 6340 |
| Chapter IX. The Theory of Parasitism | 7164 |
| Chapter X. The Tribulations of The Mason Bee | 8056 |
| Chapter XI. The Leucopses | 5120 |
