368 MR. C. WARBURTON AND MISS A. L. EMBLETON ON 
probable that these early wanderers are nearly all doomed to 
destruction, but their presence is easily accounted for. Many of 
the infested buds are not too much injured to put forth leaves 
however weakly (PI. 33. fig. 2); and if they succeed in doing 
this, the mites are deprived of their shelter and rendered home- 
less before the formation of next year’s buds. This compulsory 
quitting of buds of which the mite has not succeeded in entirely 
destroying the germinating power may be regarded as more or 
less fortuitous, and is a very different matter from the definite 
migration which appears to take place from the wholly abortive 
buds. 
As we have seen, this commenced, in 1901, about the middle 
of May. The activity of the mites attained its maximum about 
May 30, and practically ceased about the middle of June, by 
which time the arrested buds were dried up and destitute of 
lving mites. 
A very careful investigation of the behaviour of the mites 
during this migration period revealed some interesting habits 
which have hitherto escaped observation. 
Three different methods of locomotion are employed by these 
creatures in their search after new feeding-grounds. These are: 
(1) crawling, (2) adherence to passing insects, and (3) leaping. 
Crawling. 
The extremely anterior situation of the four short legs would 
seem to be ill-adapted for locomotion. Nevertheless the mite 
can crawl along quite actively, at the rate of three or four milli- 
metres, or twelve to fifteen times its own length, a minute. 
The motion of the legs is very scrambling and haphazard in 
appearance, but by wild exertion they drag the unwieldy body 
forward—an inert mass, trailing in the rear. When, however, 
the mite desires to change its direction, or to surmount an ob- 
stacle, the tail apparatus, with its muscular dise and bristles, 
comes into play. By this apparatus a hold is obtained upon the 
surface over which the mite is crawling, and the body is swung 
round, or the anterior portion is reared up and the obstacle 
surmounted. The tail-bristles are stronger and less wavy than 
they are represented in most figures of the mite, and appear to 
be accessory motile organs of no slight importance. | 
Their position in crawling may be seen in figs. 7, 20. 
