| Chapter I. The Terebinth Aphids. | 5181 |
| Chapter II. Experiments | 4740 |
| Chapter III. Exchanging The Nests | 3535 |
| Chapter IV. More Enquiries Into Mason Bees | 6696 |
| Chapter V. The Story of My Cats | 4910 |
| Chapter VI. The Red Ants | 6631 |
| Chapter VII. Some Reflections Upon Insect Psychology | 6556 |
| Chapter VIII. Parasites | 4428 |
| Chapter IX. The Theory of Parasitism | 5481 |
| Chapter X. The Tribulations of The Mason Bee | 5946 |
| Chapter XI. The Leucopses | 3642 |
