| Chapter I. The Terebinth Aphids. | 7058 |
| Chapter II. Experiments | 6982 |
| Chapter III. Exchanging The Nests | 5427 |
| Chapter IV. More Enquiries Into Mason Bees | 8881 |
| Chapter V. The Story of My Cats | 6775 |
| Chapter VI. The Red Ants | 10320 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8591 |
| Chapter VIII. Parasites | 6384 |
| Chapter IX. The Theory of Parasitism | 7195 |
| Chapter X. The Tribulations of The Mason Bee | 8093 |
| Chapter XI. The Leucopses | 5149 |
