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carnivorous larvae. Investigation proved that the latter group were, 

 in fact, living at the expense of the former, piercing the skin of one 

 after another of the phytophagous species, which proved to be Chorto- 

 phila pilipyga, and sucking the body-contents. Certain Microlepidop- 

 terous larvae which were also present shared the same fate. It is 

 evident then that Phaonia trimacidata, which has been considered a 

 cabbage pest, is not phytophagous, but on the contrary serves the 

 purpose of ridding the plant of serious enemies. 



Myospila meditabumla, F., which was observed by the author in 

 cow-dung and in the excrement of pigs mixed with various decaying 

 vegetable matter, has been described by Portchinsky as being so much 

 like the carnivorous Mydaea ancilla that the larvae of the two "species 

 were considered indistinguishable. Myospila medikibunda is un- 

 doubtedly carnivorous, feeding upon saprophagous larvae, as well as 

 those of certain small Anthomyiids and Borborids which accompanied 

 them. 



The genus Mydaea includes several carnivorous larvae. The larvae 

 of M. ancilla and M. urhana are undoubtedly carnivorous ; those of 

 M. tincta are probably so ; the larvae of M. pertusa possess the mor- 

 phology characteristic of carnivorous larvae ; a larva of M. vomitura- 

 tionis has been known to be the cause of a fatal intestinal myiasis. 

 The larvae of M. pici, M. anomah, M. torquans and M. spermophila 

 have been found as subcutaneous parasites of birds in central America. 



Hydrotaea dentipes, ¥., has already been fully dealt with and the 

 larvae proved to be carnivorous in their third instar, in the work of 

 Portchinsky referred to above. This species is particularly important 

 as preying on Musca domestica and Stomoxys calcitrans. The author's 

 investigations have confirmed Portchinsky's discoveries. H. armipes, 

 Fall., has also been described in the carnivorous larval stage by 

 Portchinsky. H. i)ieteorica, L., has been known to produce intestinal 

 myiasis in human beings. 



Muscina assimilis, Fall, is described as semi-carnivorous or omni- 

 vorous, as it can maintain life, in the absence of animal matter, upon 

 vegetable matter in a state of decomposition. It is frequently found 

 in decaying fungi or other vegetable matter, where it lives upon the 

 larvae of such Diptera as Drosophila confusa, Fannia canicidaris, L., 

 and Aphiochaeta rufipes, Mg. Muscina stahulans and M. pabulorum 

 have similar habits to M. assimilis. M. stahulans has been found 

 capable of living for a long time in the intestinal liquid of man, and the 

 larvae may cause serious injury by wounding the walls of the intestine 

 with their sharp mouth-parts. 



Portchinsky's account of the carnivorous habits of Polietes alboli- 

 neata, Fall., and of Mesembrina mystacea, L., are discussed, as well as 

 his work on Hydrotaea dentipes, regarded as an enemy of saprophagous 

 larvae. The author agrees that carnivorous larvae, and in particular 

 those of H. dentipes and Muscina, are an important factor in the 

 destruction of the house-fly, but he does not agree with Portchinsky 

 that this habit could be put to any practical use as a control method, 

 since, if the breeding places of the fly are known, it is easier to destroy 

 them or render them uninhabitable than to introduce the larvae of some 

 carnivorous species into their midst. There is also the risk of intro- 

 ducing the carnivorous species into houses if freely distributed in the 

 vicinity. It would be a decided advantage, however, to introduce 



