126 MAUD D. HAVILAND 
4. The evidence points to the conclusion that there are four 
larval instars and three moults. 
5. The larvae differ in several particulars from those of the 
families of Proctotrypoidea previously described, and there 
is considerable difference in form between the early and later 
instars. 
6. During development, which lasts about six days, the 
larva devours its host, and then pupates within the skin of the 
aphis for a further period of two weeks. 
7. Two, and possibly more, broods are reared in the season ; 
and it is probable that the hyperparasite is a considerable check 
on the Aphidius in its control of plant-lice infestation. 
8. Lygocerus, though occasionally attacked by its own 
species, was never found to be parasitised by another hymen- 
opteron. This immunity is probably due to the active move- 
ments with which the larva and pupa in the cocoon respond 
to external stimuli. 
BIBLIOGRAPHY. 
1. Ashmead, W. H. (1893).—‘‘ A Monograph of the North American 
Proctotrypidae”’, * Bull. U.S. Nat. Mus.’, vols. 44-6, pp. 1-472, 
Pls. i-xviil. 
2. Ayers, H. (1884).—‘‘ On the development of Oecanthus niveus 
and its parasite Teleas”’, ‘Mem. Bost. Soc. Nat. Hist.’, vol. iii, 
no. 8, pp. 261-81, Pls. xxiii-xxv. 
3. Berlese, A. (1909).—*‘ Gli Insetti ’’, Milan. 
4. Buckton, G. (1879).—*‘‘ A Monograph of British Aphides”, Ray 
Society’s Publications, vol. ii. 
5. Devitz, H. (1874).—* Ueber Bau und Entwickelung des Stachels und 
der Legescheide einiger Hymenoptera ”’, ‘ Zeit. wiss. Zool.’, vol. xxv, 
pp. 174-200, Taf. xii—xiii. 
6. Embleton, Alice (1904).—‘* On the Anatomy and Development of 
Comys infelix”, ‘Trans. Linn. Soc.’, vol. ix, pt. 5, pp. 231- 
54, Pls. 11-12. 
7. Forster, A. (1856).—** Hymenopterologische Studien ”’, ii. 
8. Ganin, M. (1869).—“ Beitrage zur Kenntniss der Entwickelungs- 
geschichte bei den Insecten ”’, ‘ Zeit. wiss. Zool.’, xix, pp. 381-448, 
Taf. xxx-xxxiil. 
9. Gatenby, J. Bronté (1919).—*‘ Notes on the Bionomics, Embryology, 
