192 PTILOTA. 



of tlieir foliage ; and it was feared that they woukl extirpate 

 the gromng corn and grass, and starve the cattle to death in 

 the fields. They were regarded as the harbingers of the 

 plague, and prayers were ordered to be read in all the churches 

 to avert the supposed impending calamity. In France, also, 

 the same or a nearly-allied species has so frequently appeared 

 in such prodigious numbers, entirely defoliating the forests, 

 that the legislature have promulgated several ordonnances 

 for their destruction. 



The colours of larvse are very variable ; indeed, it would be 

 very difficult to lay down many general rules respecting them. 

 It may, however, be observed, that those species which are 

 destitute of legs, and are of a fleshy consistence, have the 

 body generally of a white or dirty white colour. Many 

 caterpillars also, wdiich greatly resemble each other, produce 

 moths totally unlike, whilst moths, which are so closely 

 allied that it is almost impossible specifically to distinguish 

 them (the shark moths, genus CucuUia, for instance), are 

 different in their larvse, which are consequently resorted to 

 as affording a more certain specific character. Caterpillars 

 also vary in their colours during their growth; and Mr. 

 Sheppard has observed, that the skin of the caterpillar of 

 the privet hawk-moth, after being under ground fovu' days, 

 was changed from a vivid green to a dull red. A similar 

 change of colour also occurred in a caterpillar of the puss- 

 moth {Cerura vinula), which I endeavoured to preserve. 

 From what has been said, it will be easily conceived that the 

 colour of the caterpillar affords no criterion for judging of 

 the colours of the future moth; the most beautifully 

 coloured moth, "as Reaumur observes (Mem. i. p. 198), pro- 

 ducing the dullest coloured moths ; and vice versa. De Geer 

 has, however, given two instances in wdiich the moth preserves 

 the colours of the caterpillar ; these are the common magpie 

 moth [Abraxas grossulariata), and the green Pyralis prasi- 



