| Chapter III. The Distribution of Sexes | 638 |
| Chapter XII. The Halicti: a Parasite | 717 |
| Chapter VIII. Parasites | 611 |
| Chapter IX. The Theory of Parasitism | 646 |
| Chapter X. The Tribulations of The Mason Bee | 929 |
| Chapter III. Another Prober (Perforator) | 778 |
| Chapter XVI. A Parasite of The Maggot | 937 |
