1. Bothryoxysta curvata, Kieff., Charips victrix, Hartig, and Alloxysta erythrothorax , Westw., are hyperparasites of aphides through Aphidius (Braconidae).

2. Reproduction may be either sexual or parthenogenetic.

3. The egg is laid in the haemocoele of the host larva before the death of the aphid, and post-ombryonic development is internal.

4. A trophic membrane of hypertrophied cells is formed round the embryo.

5. The larva is, at first, hypermetamorphic ; and exhibits greater development of the chitinous cuticle than is usual in ondoparasites ; but in the succeeding stages it approximates more closely to the general hymenopterous type.

6. The development of the Aphidius is arrested at a certain point, and metamorphosis does not take place.

7. The Cynipid, when ready to pupate, makes its way out of the Aphidius, whose remains it devours, and undergoes metamorphosis within the cocoon previously woven by the latter in the skin of the aphid.

8. These forms differ in certain particulars from the entomophagous Cynipidae previously described, and the chief differences are discussed.

9. Comparison is also made of the larvae of other Hymenoptera Parasitica, particularly of Perilampus.

10. Certain problems of metabolism are pointed out, and it is suggested that respiration may be partly rectal.

11. These Cynipidae are economically injurious as they check the Aphidius in its destruction of plant-lice; but there is high mortality among the larvae owing to secondary parasitization of the Braconid by other hyperparasites.

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