| Chapter I. The Terebinth Aphids. | 4310 |
| Chapter II. Experiments | 3865 |
| Chapter III. Exchanging The Nests | 2789 |
| Chapter IV. More Enquiries Into Mason Bees | 4959 |
| Chapter V. The Story of My Cats | 4119 |
| Chapter VI. The Red Ants | 5467 |
| Chapter VII. Some Reflections Upon Insect Psychology | 5856 |
| Chapter VIII. Parasites | 3630 |
| Chapter IX. The Theory of Parasitism | 4387 |
| Chapter X. The Tribulations of The Mason Bee | 5015 |
| Chapter XI. The Leucopses | 2930 |
