It should be noted that Mr. A. Koebele introduced an Ameri- 

 can Elenclius into the Hawaiian Islands in 1903, which failed to 

 establish itself upon P. saccharicida. Evidently it took to A. 

 ipomoeae for I cannot believe that this parasite existed in the 

 islands prior to that date, or Messrs. Perkins and Giffard would 

 have detected it when collecting on Tantalus. 



In the breeding jars the adult males hatched out in the early 

 morning, between sunrise and 7 a. m., and were dead before mid- 

 day. They are very feeble upon their legs and keep their wings 

 in rapid vibration all the time they are walking. When on the 

 wing they take up a perpendicular position with their antennae 

 erect, and the tip of their abdomen turned slightly under. In 

 this position they hover very steadily around the sugar-cane stalks 

 and along the leaves, seeking leaf hoppers bearing female Elen- 

 chus. Sight seems to be the chief sense by which they detect the 

 presence of the leaf hoppers, as I have seen one hovering along 

 one side of a leaf with half a dozen stylopized hoppers on the other 

 side, only a quarter of an inch aw^ay, and apparently not knowing 

 of their presence, but should a hopper but show its antennae over 

 the edge of the leaf the Elcnchits darts towards it and hovers over 

 its back. If the hopper bears a mature female parasite, the male 

 settles about half an inch away and crawls towards the hopper, 

 vibrating its wings all the time. This generally disturbs the hop- 

 per and it moves off, the Elenchns following till it gets a chance to 

 spring upon its back and attach itself to the female. This action 

 disturbs the hopper and it flicks its abdomen to shake off the 

 parasite. Except on these occasions, the hopper appears to have 

 no antipathy towards Elenchns and is never disturbed by its 

 presence, as Polistes is reported to be by Xciios. I have never 

 seen the male Elcnchits retain its hold of the female for more than 

 six seconds, generally it is attached only two or three seconds. 

 I am unable to say if fecundation takes place during this time or 

 exactly how copulation takes place ; evidently the tip of the 

 abdomen is inserted into the brood-chamber. 



In captivity the larvae of the first stage, triungulins, never 

 lived longer than twenty-four hours, numbers being drowned in 

 the moisture upon the glass sides of the breeding jars; moisture 

 upon the leaves does not appear to have such a fatal effect upon 

 them. No doubt under more favorable conditions in the open 

 air the triungulins are able to exist for a much longer period 

 before entering their hosts. 



The method by which the triungulins enter their hosts I was 

 not able to observe. When they have entered their host and em- 

 bedded themselves among the fat bodies of the abdomen or thorax 

 they begin to swell and histolysis sets up, the skin splits along 



