66 



AUTUMN AND WINTER 



depicted on the moth's thorax, it is, of course, a purely 

 chance similarity. The picture of the death's-head is alarm- 

 ing only to mankind ; and it is impossible that the moth's 

 markings should have been developed in the comparatively 

 short period of man's existence as a formidable species, and 

 as the result of any struggle between them. The death's- 

 head mark is in fact not always a protection ; for the anxious 

 potato-lifters make an end of the menacing creature with a 



fork. Another un- 

 canny feature of the 

 death's-head hawk is 

 its unique possession 

 of a voice. Alone 

 among our moths and 

 butterflies, it can 

 squeak. Both the 

 winged insect and the 

 pupa can make this 

 sound ; and it is not 

 known how they do 

 it. The moth has 

 been thought to emit 

 the sound by the friction of the thorax against the abdomen, 

 after the fashion of some beetles, or by forcing air through 

 the thorax, head and trunk. But the fact that the pupa 

 can also emit the sound makes it very unlikely that the 

 latter explanation is correct. The mail of a pupa fits too 

 close to make any such passage of air seem possible ; but 

 it can writhe its abdominal segments, so that the sound 

 seems more likely to be produced by friction in that part of 

 the body. 



The large greenish caterpillars of the buff-tip moth are 

 often seen in late August and September as they descend 



CATERPILLAR OF DEATH'S-HEAD MOTH 



