THYSANOPTERA. 



CHAPTER I. 



TllRiriLJi. 



The rather long name which is given at the head of this chapter 

 is formed from two Greek words, and signifies "tassel-winged," 

 because the wings of the insects are furnished with long tassel- 

 like hairs. They have no network-like pattern upon them, and 

 are laid Hat upon the hack when the insect is at rest, one wing 

 lying almost completely over the other. 



The exact position of these insects is not easily decided. It 

 is true that they are very small, but then the microscope has 

 abolished all difficulties in that direction, while the discovery of 

 certain foreign species, such as that which is here figured, has 

 rendered examination comparativel}^ easy. The structure of the 

 mouth forms the principal obstacle to the systematic arrange- 

 ment of these insects. They have mandibles, but these organs 

 are modified into a pair of slightly curved and very slender 

 bristles, technically called " setiform," from the Latin word 

 seta, a bristle. 



Mr. Westwood, who was the first to describe the parts of the 

 mouth, sums up the description in the following words : — " The 

 relations of this order are very difficult. The nature of the meta- 

 morphoses would unite it with the Orthoptera or Hemiptera, 

 M'liile the structure of the wings and mouth removes it from both 

 these orders. The mouth, indeed, seems to be of a character 

 almost intermediate between the Mandibulata and the Hau.5tel- 

 lata ; the setiform mandibles are very like those of the Hemi- 

 ptera, whilst the general disposition of the other parts of the 

 mouth are more like those of a maudibulated insect. It appears 



