C50RNELL UNIVERSITY EXPERIMENT STATION BULLETINS. 263 



honey-dew; some is assimilated, and the waste matter voided as excrement. 

 The adults, however, seem to secrete no honey-dew, all the food being 

 assimilated. Consequently the adults void considerable quantities of excre- 

 ment, much more than do the nymphs. 



The honey-dew and excrement are very different substances, but the fact 

 does not seem to have been before observed. The honey-dew is a clear 

 water-like liquid and forms into globules when secreted. The excrement, 

 however, is a whitish semi-solid substance which is voided in long cylin- 

 drical strings, or minute whitish balls which roll from the anus like quick- 

 silver globules. 



In the adult, the anus is situated upon the dorsal surface, in the female 

 it is just at the base of the upper genital plate (Fig. 6 a); in the 

 male, the anus opens upon the tip of the upper plate (Fig. 5 a). 

 In voiding the excrement, the male twists the abdomen downward so that 

 none of the whitish substance adheres to the anus. The females, however, 

 can not thus twist the body and some of the excrement frequently adheres 

 as whitish flakes; or not dropping freely, it sometimes forms into a string 

 often reaching half an inch in length. In the nymphs the anus is situated 

 on the venter near the caudal end (Fig. 2 a) of the abdomen. It 

 is surrounded by a ring of large wax-cells; a similar ring also surrounds 

 the anus of the adult female. The excrement of the nymphs is usually 

 voided in a string. It has of ten been seen in the midst of a globule of 

 honey-dew secreted by the same nymph; thus clearly demonstrating that 

 the two secretions are distinct. • _ 



Many observations were made to discover, if possible, the manner 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 around the 

 edge of th£ abdomen, or from excretory pores on the dorsum of the 

 abdomen. Globules 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 German 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 commonly supposed. Honey-dew 

 thus seems to be what might rightly be called the fluid 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 fruitgrowers to the pest. 

 The result was that when the insect appeared in enormous numbers early 

 in the spring of 1891, fruitgrowers were at a loss what to do and how to do 

 it; and entomologists could only suggest methods which seemed practica- 

 ble. In most cases the attempts to combat the pest were begun too late; 

 most of the damage had been done, the fruit and new growth being severely 

 blighted; the nymphs had covered themselves with honey-dew, and the 

 very active summer adults had appeared. After several unsuccessful attempts 

 with various substances such as kerosene emulsion, solutions of whale-oil 

 soap, fir-tree oil, and carbolic acid, and London purple and Paris green, 

 the afflicted fruitgrowers gave up in despair. Nothing seemed to check 



