OF THK MALTESE ISLANDS. 49 



bonded stoves ; refuse of all kinds, especially such as occuiTed in dark damp 

 places ; the refuse " tips," and the roots of plants along the coast, especially in 

 localities which were known to be badly infested with the flies ; the decayed 

 stems of the Prickly Pear ( Opuntia sp.) ; collections of stone and rock in shady 

 places in gardens and elsewhere : freshly excavated earth and rock : the empty 

 shells of molluscs (chiefly Helix sj).) foimd in caves and other sheltered situations ; 

 refvise in caves vvhich were used as stables for oxen and other domesticated 

 animals, and the faecal matter which was found in those which had been used 

 as latrines : the roots of trees, ivy and flowering plants which were kept 

 moistened by constant supplies of water ; the accumulations of leaves in damp 

 places, &c. ; litter from rabbit-hutches, consisting chiefly of faecal matter, 

 especially at Casa Leoni, where the adult flies were invariably found associated 

 with these animals. 



Although one failed to discover either larvae or pupae in any of these situa- 

 tions, it does not prove conclusively, in my opinion, that these insects do not 

 breed in some of them, especially as Grassi (3) has found that in Italy the larvae 

 of P. papatasii live in dark damp spots amidst all kinds of refuse in underground 

 places such as cellars, and particularly on the sides of drains which are kept 

 moist by occasional splashes of dirty water. 



Other investigators in Malta have met with results similar to my own. Lieut.- 

 Colonel C. Birt, K.A.M.C. (2), who collected the most varied materials, states 

 that he did not succeed in detecting the ova or larvae in any of the samples, 

 " nor has the adult P. papatasii ever hatched out from larvae which might have 

 been hidden in the materials." Captain Marett (6) has also made extensive 

 search for the larvae and pupae in similar places and in similar materials, and 

 has failed to find a single example of the insect in any of its stages. In so far 

 therefore as our present knowledge is concerned, the only conclusion which can 

 be drawn from the investigations in Malta is that the chief breeding-places of 

 the Papataci flies (P. piapafasii and P. jjerniciosus) are the crevices between the 

 loose rocks in caves, stone walls, bastions and similar situations. 



The task of finding such minute objects as either the larvae or pupae of these flies 

 is, however, very great ; of the two, the larvae are perhaps the more conspicuous, but 

 these have the remarkable habit of flicking themselves from off the surface of the 

 stone or other objects when exj)Osed to light, and in this way numbers may escape 

 detection even under the most practised eye. The pupae are the more difficult 

 to detect, as, apart from their minute size, the colour so exactly harmonises with 

 the colour of the rock to which they are attached that they are rendered almost 

 invisible, and when detected appear only as a naturally formed granular projec- 

 tion on the surface of the stone. In every sense, therefore, they are highly 

 protective forms, and numbers must necessarily escape detection, more especially 

 when artificial light has to be employed in searching for them. Bearing these 

 facts in mind, lai'ge quantities of detritus were collected from many and varied 

 sources so that it could be examined under moi'e favourable conditions, but in no 

 single instance were these insects found in either of their preliminary stages, 

 though a lens of low magnification was almost invariably employed in searching 

 for them. Quantities of the detritus were also kept in large vessels in the hope 

 that adult flies might be successfully reared fi-om it ; in this again complete 

 19127 D 



