44 INSECTS AFFECTING THE ORANGE. 



m search of sucb lurking places, however readily they accept the pro- 

 tection when foniul. 



Theobservedl'act that Scale-insects spread most rapidly in the direction 

 of prevailing winds has often been verified, and has led to the belief 

 in direct transportation by the winds, as the most important agency in 

 their dissemination. This poi)ular theory is thus stated bj" a writer: 

 '• Now, in the spring and fail, jnst when the insects are hatching and 

 most numerous, we have our heaviest storms. * " * During 

 one of these storms I have often seen leaves, twigs, and sometimes 

 whole branches taken up and carried whirling through the air for a 

 quarter of a mile or further. How easy, then, would it be for these 

 microscopical insects, bat a few atoms in weight, to becai ried tor miles."* 



The gentle southeast trade-winds of Florida and the storms which 

 are occasional, and, fortunately, somewhat lare visitants, are very 

 different phenomena. While the influence of Ihe former is sometimes 

 seen in the more rapid spread of the Scale-insects towards the north- 

 west, it has never been observed that a sudden extension of the pesi 

 has followetl any of the violent or long-continued wind storms on record. 



That tempest-borne branches and leaves might carry the inlection 

 to a distance cannot of course be denied, but the dissemination of Scale- 

 insects, continues without interruption at all seasons and in 4dl i)arts 

 of the State, a process of such constancy and regularity, cannot be 

 attributed in any great measure to the titful agency of occasional storms. 



Nor can it be by direct transpoitation that the trade- winds assist in 

 spreading Scale-insects, for winds of moderate ioice are not comi)etent 

 to dislodge the young lice from the ])l;ints. Of this any one may be 

 convinced by trial with a bellows or with the breath. Minute and in- 

 significant in weight though they are, taey cling with tenacity to the 

 bark, and the pressure of air upon their thin bodies only serves to press 

 them into closer contact with the surface. 



It is rather to the indirect action of the wind, to the influence which 

 it exerts u[)on the flight of insects and other winged animals which 

 transport, Scale insects, that we must look for an explanation of the ob- 

 served phenomena. 



And particularly is this influence of the wind felt in the case of spiders, 

 most of the species of which are dependent upon the wind in their mi- 

 grations. For, although wingless, they are enabled by means of the 

 buoyancy of their Aveb and the power which they possess of reeling it 

 out upon the wind to biidge long gaps from tree to tree, and even to 

 copy the flight of winged animals. 



The gossamer spider makes its aerial voyages by clinging to a light 

 tangle of web, on which, as by a parachute, it is borne to great distances 

 by the wind. 



Many species have this habit of the gossamer. Some, however, use, 

 instead of a tangle, long lines of web which are cast out upon the wind 

 to a distance of several hundred feet, until their buoyancy becomes 

 * Ashmead, Orange Insects, page 3, 



