| Chapter I. The Terebinth Aphids. | 7007 |
| Chapter II. Experiments | 6932 |
| Chapter III. Exchanging The Nests | 5383 |
| Chapter IV. More Enquiries Into Mason Bees | 8817 |
| Chapter V. The Story of My Cats | 6738 |
| Chapter VI. The Red Ants | 10115 |
| Chapter VII. Some Reflections Upon Insect Psychology | 8481 |
| Chapter VIII. Parasites | 6330 |
| Chapter IX. The Theory of Parasitism | 7159 |
| Chapter X. The Tribulations of The Mason Bee | 8048 |
| Chapter XI. The Leucopses | 5115 |
