170 
Dacnusa areolaris Nees , etc. 
with a pair. There are now nine pairs of open spiracles on segments 2, 4-11, 
and, in addition, a closed spiracular trunk on segment 3 (Fig. 3). 
The internal structure approximates closely to the type of hymenopterous 
larvae in general, and calls for no particular comment. 
Dacnusa areolaris undergoes metamorphosis within the host’s puparium, and 
no cocoon is woven. The period of pupation is usually about two weeks. The 
development of the parasite is however very closely correlated with that of 
the host, as may be seen by the accompanying table: 
Pupation 
Emergence 
Emergence 
of host 
of host 
of parasite 
June 1 
June 24-25 
June 25-27 
„ 5 
„ 25-26 
„ 26-27 
„ 7 
„ 26 
„ 26 
„ io 
July 1 
July 1 
All the puparia collected on one day were set apart, and the emergences 
of hosts and parasites noted separately. It will be seen that the development 
of the parasite from the first moult to the emergence of the imago is one or 
two days longer than the puparial period of the host. In the first collection, 
where the host’s emergence was delayed for five days, the emergence of the 
parasite was correspondingly deferred. 
The imagos lived for five or six days in captivity, when fed on sugar and 
water. It is possible that this is a further correlation between parasite and 
host, for, as previously remarked, the fife of the latter is short, and oviposition 
takes place soon after emergence. In parasitised populations, the flies thus 
emerge and oviposit a day or two before the Braconids appear. Hence there 
will be a sufficiency of hosts by the time the parasites are ready to deposit 
their eggs. 
GENERAL REMARKS. 
The genus Dacnusa was named by Haliday in 1839, although certain of the 
species now included in it were described earlier by Nees von Esenbeck. 
Marshall (1885) in his Monograph describes 29 forms, but he remarks that some 
of these are ill-defined, and that their systematic position requires further 
investigation. The species whose hosts are known have all been reared from 
Phytomyzid or Agromyzid larvae. 
Other Braconidae whose fife cycles have been described include a few species 
which are endoparasitic in dipterous larvae. 
Keilin and Picado (1913) published an account of the larval forms of 
Diachasma crawfordi, parasitic on the fruit fly Anastrepha striata Shin. 
Pluvinel (1914) observed the development of Adelura. gahani, a parasite 
of a Phytomyzid. 
Alston (1920), in a detailed bionomical study, described the larva of 
Alysia manducator Panz., a parasite of the blow-fly. 
The larva of D. areolaris , with its trophic membrane, much resembles that 
of the Chalcid, Smicra clavipes, figured by Henneguy (1892), and endoparasitic 
