| Chapter I. The Terebinth Aphids. | 5798 |
| Chapter II. Experiments | 5449 |
| Chapter III. Exchanging The Nests | 4078 |
| Chapter IV. More Enquiries Into Mason Bees | 7346 |
| Chapter V. The Story of My Cats | 5537 |
| Chapter VI. The Red Ants | 7981 |
| Chapter VII. Some Reflections Upon Insect Psychology | 7181 |
| Chapter VIII. Parasites | 5109 |
| Chapter IX. The Theory of Parasitism | 5996 |
| Chapter X. The Tribulations of The Mason Bee | 6640 |
| Chapter XI. The Leucopses | 4116 |
