OF THE MALTESE ISLANDS. 49 
bonded stores; refuse of all kinds, especially such as occurred 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 molluses (chiefly eliz sp.) found in caves and other sheltered situations ; 
refuse in caves which 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. papatasz 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, R.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. papatasi?i 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. papatasii and P. perniciosus) 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 exposed 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, large quantities of detritus were collected from many and varied 
sources so that it could be examined under more 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 from it; in this again complete 
19127 D 
