| Chapter I. The Terebinth Aphids. | 6996 |
| Chapter II. Experiments | 6911 |
| Chapter III. Exchanging The Nests | 5375 |
| Chapter IV. More Enquiries Into Mason Bees | 8806 |
| Chapter V. The Story of My Cats | 6723 |
| Chapter VI. The Red Ants | 10091 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8468 |
| Chapter VIII. Parasites | 6311 |
| Chapter IX. The Theory of Parasitism | 7145 |
| Chapter X. The Tribulations of The Mason Bee | 8035 |
| Chapter XI. The Leucopses | 5107 |
