420 Annals Entomological Society of America [Vol. IX, 



get a coating of black, sooty mold, which grows in the honeydew 

 excreted by the aphids. Both the gray secretion and the sooty 

 mold fungus greatly injure the appearance of infested Monterey 

 pines. Frequently, when a colony of Lachnus is rubbed off, 

 small, discolored areas where the beaks have penetrated are 

 disclosed. A large specimen which has been parasitized and 

 killed is shown in Photograph IX. This also shows the final 

 effects of the work, a discoloration of the needle where the 

 insect had sucked. The reddish area extends entirely around 

 the needle. A light green area is shown on either side of this 

 red spot. 



Essigella was found to be an active species, the individuals 

 sucking for a day or two in a place, retreating to a protected 

 position at the base of the needle bundles at the slightest dis- 

 turbance, and also remaining hidden there in wet, windy 

 weather. Detailed, daily observations of all individuals on a 

 number of selected needles were made for a period of six weeks. 



Selecting examples at random from our records of Essigella, 

 we find that punctures were made during this comparatively 

 short period in 83 places on one leaf, and 74 on another, though 

 the number of aphids on a leaf at the time the observations 

 were made was, on the average, five. Conclusions drawn from 

 the observations are as follows : 



(1) Out of about 6400 feeding positions observed, but few 

 left any mark that was visible to the eye, except sooty mold. 

 This was removed at the end of the observation period to make 

 it possible to find any markings there might be beneath. 



(2) Two feeding positions, in each case of one day only, were 

 followed by an exudation of gum. We made sections to find 

 the cause of the exudation. Both were shown to be caused by a 

 puncturing of the resin ducts. This is apparently accidental, 

 as they would be as poor feeding ground as could be found in the 

 leaf. 



(3) Three cases of infiltrated spots occurred. One was 

 accompanied by gumming. All were the same as other infil- 

 trated spots found on aphid- or coccid-infested pines. 



(4) There were ten small, light colored spots which, in every 

 case, followed a period of sucking of two or more days. 



Experiments were tried to determine whether infiltrated 

 spots could be produced artificially. Selected digger pine 



