432 



iiii<>rati]iii birds, oi- hi<ili winds or ocean cnrrents to account 

 for the an-ival lici-c of sn(di delicate insects. 



P)ii'd miiirations hither ai'e niostlv, if not entirely, from 

 .Vnierica, and the Hawaiian jnniping plant lice and leaf ho]v 

 pers do not seem to have come from there. Windstorms sel- 

 dom, if ever, blow from present land areas of the South Tacitic 

 to these Islands, nor do ocean cnrrents come this way from that 

 part of the world. However, we mnst consider that not more 

 than one ancient inmiigrant of the Psyllidae and probably only 

 three or fonr of leaf hoppers succeeded in establishing them- 

 selves here during several million years. It must be admitted 

 that what now seems impossible might have succeeded by chance 

 once in a million years. It is conceivable that once in several 

 nullion years a windstorm might have carried a leaf with galls 

 containing nymphal psyllids and dropped the leaf in an Ha- 

 waiian forest of the same kind of trees — an exceedingly rare 

 chance ! — whereupon the insect might establish itself. Another 

 psyllid species has been a less ancient immigrant, but how it 

 arrived or Avhen it is not possible even to surmise. This one 

 apparently has not given rise to other species than one which 

 now lives on the native palms, but nevertheless seems to have 

 arrived a long time ago. 



The JuMPixa Plant Lice. 

 Psyllidae, or Chermidae (Homoptera). 



The jumping plant lice (Psyllidae or Chermidae) consti- 

 tute a family of the homopterous sucking bugs, being allied to 

 the true plant lice and scale bugs and also to the leaf hoppers 

 and lantern flies. They are small insects, from 1-32 to 1-4 

 inch in length, with four wings, the third pair of legs usually 

 developed for leaping from which hal)it the first part of their 

 popular name has been derived. Their superlcial resemblance 

 to true plant lice (A])hi(lidae) has suggested the latter part of 

 their name. 



The ])sylli(ls live l)y sucking the. juice from plants by 

 means of their slender, ])ointed beak which arises from the 



