BIPTERA (two-winged FLIEs). 75 



DiPTERA COLLECTED IN THE TrOPICS : 



Attacks by Ants — Mould — Transmission to England. 



In the tropics boxes of pinned insects are very liable to the attacks 

 of minute ants, which, if they once gain access to a box unobserved, 

 will scon play havoc with its contents. In Brazil it has been found 

 that ants can be prevented from entering insect-boxes by smearing 

 the outside round the line where the box opens, or any other possible 

 place of entrance, with andiroha oil, repeating the process as often 

 as necessary ; similar methods might be employed elsewhere in case 

 of need. 



Mould, however, is an even greater enemy to collections of Diptera. 

 Pinned specimens of Diptera, like those of other insects, rapidly 

 develop mould during the rainy season in tropical countries ; and 

 since mouldy specimens are practically worthless for purposes of 

 scientific determination, Diptera should always he sent home as soon 

 as jyossible after being collected. The risk of mould may, however, be 

 diminished by pinning in a corner of the box a small piece of sponge 

 saturated with the strongest carbolic acid, which should be con- 

 stantly renewed. The greatest care must be taken to prevent 

 specimens getting loose and rolling about in transit, since in this 

 way a single loose disc might easily do irreparable injury to many 

 other specimens in the box. To prevent this the pins supporting 

 the discs should be inserted as tightly as possible into the cork- 

 carpet or pith, and they should all be driven in to the same level, 

 after which a sheet of soft paper (newspaper does very well) can be 

 Jixed into the box, resting on the heads of the supporting pins, in 

 order to minimize the damage should a disc happen to get loose. 

 The box containing the specimens should be well wrapped in cotton- 

 wool or similar material, to secure it from shocks on the journey, 

 and firmly packed in an outer case for transmission (by parcel-post 

 if possible and the package is not too large) to England. 



Number of Specimens of each Species required. 



At least half a dozen specimens of each sex of a species should, if 

 possible, always be obtained, and a good look-out should be kept for 

 specimens showing any abnormality in structure, coloration, or 



