The Processionary : Meteorology 



During this period of ten days, the garden 

 caterpillars made no sortie on the pine-trees. 

 True, the weather was changeable. There 

 were a few showers of fine rain and some 

 violent gusts of the mistral; but more fre- 

 quently there were days and nights when the 

 sky was superb and the temperature moder- 

 ate. The prudent anchorites would not al- 

 low themselves to be caught. The low pres- 

 sure peristed, menacing them; and so they 

 stopped at home. 



In the greenhouse things happen rather dif- 

 ferently. Sorties take place, but the staying-in 

 days are still more numerous. It looks as 

 though the caterpillars, alarmed at first by the 

 unexpected things happening overhead, had 

 reassured themselves and resumed work, feel- 

 ing nothing, in their shelter, of what they 

 would have suffered out of doors — rain, snow 

 and furious mistral blasts — and had then sus- 

 pended their work again when the threats of 

 bad weather increased. 



There Is, indeed, a fairly accurate agree- 

 ment between the oscillations of the barome- 

 ter and the decisions of the herd. When the 

 column of mercury rises a little, they come 

 out ; when It falls they remain at home. Thus 



10.3 



