| Chapter I. The Terebinth Aphids. | 2421 |
| Chapter II. Experiments | 2083 |
| Chapter III. Exchanging The Nests | 1419 |
| Chapter IV. More Enquiries Into Mason Bees | 2650 |
| Chapter V. The Story of My Cats | 2227 |
| Chapter VI. The Red Ants | 2105 |
| Chapter VII. Some Reflections Upon Insect Psychology | 3736 |
| Chapter VIII. Parasites | 1857 |
| Chapter IX. The Theory of Parasitism | 1769 |
| Chapter X. The Tribulations of The Mason Bee | 2677 |
| Chapter XI. The Leucopses | 1353 |
