| Chapter I. The Terebinth Aphids. | 4209 |
| Chapter II. Experiments | 3766 |
| Chapter III. Exchanging The Nests | 2731 |
| Chapter IV. More Enquiries Into Mason Bees | 4874 |
| Chapter V. The Story of My Cats | 4036 |
| Chapter VI. The Red Ants | 5331 |
| Chapter VII. Some Reflections Upon Insect Psychology | 5772 |
| Chapter VIII. Parasites | 3521 |
| Chapter IX. The Theory of Parasitism | 4298 |
| Chapter X. The Tribulations of The Mason Bee | 4947 |
| Chapter XI. The Leucopses | 2882 |
