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Transactions of the Royal Society of South Africa. 
lateral hooks and a large pharyngeal sclerite, but there is no separate inter- 
mediate sclerite (Fig. 6). The tracheal system is well developed, meta- 
pneustic, but without the hard, horny spiracular plates usually present in 
muscid larvae. The larval antennae (Fig. 7, a) are small and inconspicuous 
and of the usual dipterous form. At each end of the larva there are a 
number of peculiar sensory papillae. Those at the anterior end are long and 
conspicuous and are armed at the tip with a number of minute blunt cones 
Fig. 3. — Larva of Braula caeca. — $p. Sensory papillae, ba. Buccopharyngeal armature. 
tr. Trachea, fb. Fat body. mt. Malpigliian tube. st. Spiracle. x 30. 
(Fig. 7, c), whilst those at the posterior end are shorter and armed each with 
a single sensory hair (Fig. 7,b). 
The drone larvae from the cells containing the parasites seemed to be 
quite normal and healthy. The contents of the alimentary canal of the 
dipterous larvae were carefully examined and found to consist mainly 
of pollen, the characteristic pollen grains from the black wattle being 
especially abundant and easily recognised. The drone larva's stomach was 
found to contain exactly similar food. Hence there seems little doubt but 
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