The Pear Tree Pstlla. 245 



In tJie adult, the anus is situated upon the dorsal surface. In 

 the female it is just at the base of the upper genital plate i,Fig. t>, 

 a, page 241); in the male, the anus opens u})on the tip of the 

 upper plate (Fig. 5, a, page 241). In voiding the excrement, the 

 male twists the abdomen downward so that none of tihe whitish 

 substances adheres to the anus. The females, however, can not 

 thus twist the body and some of the excrement fi'equently adheres 

 as whitish Hakes; or not dropping fi'eely, it sometimes foiins lubo a 

 stiing often reaching one-half an inch in length. In the nymphs tihe 

 anus is situated on the venter near the caudal end (Fig. 2, a, 

 page 233) of the abdomen. It is surrounded by a ring of large 

 wax-cells; a similar ring also suiTounds the anus of the adult 

 female. The excrement of the nymphs is usually voided in a 

 string. It has often been seen iu the midst of a globule of honey- 

 dew secreted by the same njTuph; thus cleai'ly demonstrating that 

 the two secretions are distinct. 



Many observations were made to discover, if possible, the man- 

 ner in which the honey-dew was secreted by the nymphs. It has 

 been supposed that the secretion came, either from the long so 

 called wax-hairs ai-ound the edge of the abdomen, or from excre 

 tory pores on the dorsum of the abdomen. Grlobules of honey- 

 dew were, however, seen attached to the nymphs in such a position 

 that it seemed very improbable that it came from either of the 

 above sources; it seemed that it must have been secreted from 

 the anus of the nymph. A Grerman observer now asserts that 

 the honey-dew secreted by the common plant-lice or Aphids 

 comes from the anus, and not from the honey-tubes as comnjonly 

 supposed.* Honey-dew thus seems to be what might rightly be 

 called the Huid excrement of the insect. 



Methods^of Preventing^the^Ravages of this Pest. 



All of the attempts to prevent the ravages of this pest during 

 1891 were ineffectual. This was due, in large part, to a lack of 

 knowledge of the life history and habits of the pest. No severe 

 outbreak had occurred within recent years which would call the 

 attention of the finiit growers to the pest. The result was that 



* M. Busgen Jenaische Zeitschrif t XXV, 339-428 (1891). 



