DAMAGE CAUSED BY ANIMALS. . 169 



although this does not usually take place until after the devasta- 

 tions have passed their culminating point. 



The hairy caterpillars are by no means sensitive to either wet 

 or cold. But nature sometimes comes to the assistance of the 

 sylviculturist with parasitic fungoid diseases, to which the cater- 

 pillars often succumb in large numbers, especially in soft, damp, 

 humose soil, so that sometimes all of them observed in their winter 

 quarters are found to be dead. 



80. The Black Arches, " Nun" or Spruce Moth, Bomlyx (Liparis) 



monacha. 1 



(Vide Plate II. fig. 16.) 



When extended, the wings of the female moth have a span of 

 1*6 to 24 inches ; the male is smaller, and also easily distinguishable 

 by its beautiful double-feathered antennae. The outer wings and 

 upper part of the body are in both genders white, with numerous 

 deeply-arched zigzag stripes, varying from brownish-black to black 

 in colour ; the lower pair of wings are brownish-grey, with bright 

 black-dotted edges ; the abdomen is mostly of a beautiful rose- 

 colour, with black horizontal or transverse bands, but is also at 

 times more of a blackish tinge. 



The caterpillar, which is about 1'6 inches in length when full- 

 grown, is of a dirty-green colour on the lower side, and whitish- 

 grey to reddish-grey on the upper ; along the back there is a 

 broad grey stripe, which commences with a heart-shaped black 

 patch on the second ring or section of the body, but narrows, and 

 is interrupted by a broad light patch on the seventh and eighth 

 rings. On each section of the body there are six small knob-like 

 hairy warts, of which the two first, on the first ring, tower above 

 the others, whilst those to the right and left of the back stripe are 

 blue, and constitute a characteristic sign for the recognition of 

 this caterpillar, which often varies exceedingly in colour. 2 



The densely-haired chrysalis, at first of a greenish colour, but 



1 For an exhaustive account of this insect, and of the ravages committed by it in 

 the Spruce Forests of Bavaria during 1889-91, see the Translator's Report in the 

 Transactions of the Highland and Agricultural Society of Scotland for 1893. Trans. 



2 Melanic sports are particularly frequent, occurring mostly in Scots Pine woods. 

 This is supposed to be a natural effort of adaptation to the darker stems of the 

 Pine trees, in order to protect the insects from enemies. Trans. 



