DEVELOPMENT OF A HYMENOPTEROUS PARASITE 529 
.THE LARVAL TYPES 
The first stage larvae of the Hymenoptera in which hypermeta- 
morphosis is known fall into ten quite distinct types. They are 
distributed as follows: one in the Vespoidea, two in the Ichneu- 
monoidea, four in the Chalcidoidea, one of which also occurs in 
the Ichneumoniodea, three in the Proctotrypoidea and one in 
the Cynipoidea. 
The Chrysidiform larva found by Ferton in Chrysis dichroa 
resembles the planidium type in its heavy chitinization, definite 
head segment and external feeding habit. But the curiously 
modified caudal segment, which is bifurcated with the tips of 
the two divisions bent inward, readily distinguishes it from any 
of the others. 
The first stage in the post-embryonic development of Agrio- 
typus armatus, has been called the agriotypiform larva. Its 
curiously irregular outline is well in keeping with the extraordi- 
nary aquatic habits of the adult and like none of the other 
hymenopterous larvae with which I am acquainted. 
A larval type with a more or less elongated caudal segment 
has been named the caudate larva. Table 1 shows it to be well 
distributed in the families Ichneumonidae and, Braconidae of the 
Ichneumonoidea and also to occur in the family Encyrtidae of 
the Chalcidoidea. The caudal appendage may be extremely 
attenuated as in Anomalon circumflexum, Limnerium validum, 
and Encyrtus aphidivorus, or very short as in Aphidius rosae 
and Ageniaspis f. prasincola. Again it may be enlarged into a 
rounded vesicle as in the young larva of Apanteles glomeratus 
and the second larval stage of Microgaster nemorum. Another 
larva which may represent a distinct type is found in Praon 
simulans. In addition to a short blunt, dorsal, caudal append- 
age it possesses a pair of shorter more delicate and more ven- 
tral appendages. The fourth to the thirteenth segments bear 
a single row of bristles posteriorly, much as in the cylindrical 
larva of Teleas. - 
The caudate larva is, so far as known, an internal parasite, 
without a functional tracheal system. Ratzeburg (’44) and Tim- 
berlake (12) have suggested that the modified caudal appendage 
