May 1, 1S70.] 



HARDWICKE'S SCIENCE-GOSSIP. 



99 



THE SAND-FLY AND ITS PARASITE. 



T WISH to call the attention of readers of Science- 

 -*- Gossip to an exceedingly common, because 

 abundant, two-winged fly found on the seashore, 

 and I dare say many other places. 



Any one visiting the seaside cannot but be struck 

 with the abundance of a greyish-black two-winged 

 fly that flits hither and thither. Not very large, 

 about the size of the ordinary house-fly (but some- 

 what less). If the said visitor have either the time 

 hanging heavily upon him, or a taste for natural his- 

 tory, let him catch one of these flies. If of the first 

 character, I say, "let him catch," &c, and, unless 

 more clever than the general run of idlers, he'll have 

 something to do which will no longer cause the time 



Fig. 101. The Sand-fly magnified. 



to hang heavy. More agile, cunning, provoking 

 little creatures I do not know. Here is one. 

 cautiously approaching, and stooping down, you very 

 carefully bring your hand within reasonable distance, 

 that you may be sure of your victim. Just one inch 

 nearer. " Bah ! he's gone." Try another. " Got 

 him ? " ei Well, no ; but I'll try again." Ay, try 

 my dear friend. Don't permit such a little (aggra- 

 vatingly little) wretch to beat you. "So, so; you've 

 tried your skill on many, how many captured ? " If 

 very patient (be sure you don't lose your temper, 

 though) you may succeed in getting one in six ; and 

 at any rate, if you can in a couple of hours show a 

 score you'll be more fortunate than some that I wot 

 of. Last week I met with some boys who evidently 

 did not know what to do with themselves ; so I 

 promised them a penny for each fly they brought 

 me within the next hour. Such a shout, and I fancy 

 such visions of good things to come, that I fear they 

 took me for a fool. To work they went, however, 



and then made " dabs 

 attempts, one gave it 



" at the sand, 

 up as being 



After a few 

 ;c No good." 



Another became suddenly virtuous, saying, " 'Twas 

 a shame to kill poor flies." A third kept manfully 

 at it ; how long I cannot say, for I went elsewhere. 

 Returning in some hour and a half, he brought me 

 one poor, unfortunate, straggling blue-bottle, saying, 

 " He'd tried hard, but could only get hold of this 

 one." A fly is a fly : he got a penny, though not for 

 the proper article. 



But I'm forgetting my work. If the sea-side 

 visitor be accustomed to natural history studies, he 

 will first watch the ways of the little creatures, and 

 then, no doubt, will soon have one either in his net 

 or hand. Well will he be repaid. At first blush, 

 there is nothing to distinguish it from many an- 

 other dipterous insect; but just give the little lilting 



Fig. 102. The Parasite of the Sand-fly magnified. 



thing a smart nip, and you transmogrify an unin- 

 teresting-looking fly into one of our modem fine 

 ladies, dressed completely in gay garnishing, and set 

 off by a handsome chignon of the most modish build. 

 Taking a more careful survey, he will see how this 

 change is brought about. A movement on the fore 

 part of the head is observed, an inflation is seen 

 going forward, until a bladder-like excrescence is 

 formed, in some cases nearly as large as the head, 

 and in some larger even than the head itself. This 

 bladder is covered with stiffish spines closely set 

 together, and appears to be connected with the 

 suctorial apparatus ; though what is its use I am 

 unable at this stage of my observations to say. 

 Judging from comparison with the dung- fly, I should 

 say that it is closely allied to it ; and, indeed, there 

 may be seen some indication of similarity between 

 the two in respect to the excrescence above spoken 

 of. 



Further examination has brought to light the fact 

 that other flies, besides those mentioned above, are 



f 2 



