10 



is very clearly seen when the tip is inserted into the tissues of the 

 leaf. 



BRACHYPTEROirs OR FLIGHTLESS FORM OF THE ADULT LEAF- 

 HOPPER. 



4. At certain seasons of the year, in certain localities at least, 

 and perhaps in all, a distinct form of the leaf-hopper appears, dif- 

 fering very greatly from the ordinary adult. This fomi is remark- 

 able for the fact that the wings are so little developed as to be 

 unfit for flight and the characteristic markings of the fully-winged 

 individuals are lost. Tn fact, no one at first sight would suppose 

 the short and long winged forms to belong to the same species, 

 the tegmina, or upper wings, of the former not extending so far 

 back as the tip of the body, while the lower pair are aborted 

 into scarcely visible lobes. 



rolymorphism in the development of the wings, aiTecting 

 also often other parts of the body is a well-known feature of the 

 Delphacid leaf-hoppers, and may be seen in other Hawaiian 

 species. This appearance of a single species under two or more 

 apparently totally distinct forms adds greatly to the difficulty 

 of the student in determining the identity of these leaf-hoppers. 



One point in connection with this flightless form is worliiy of 

 notice. Although the insect has not been with us for study for a suf- 

 ficiently long time for us to^ speak with certainty on the point, yet, so 

 far, the worst attacks of leaf-hopper have always followed or been 

 partly coincident with the production of these flightless females, 

 that is to say, during the colder months of the year, or in the 

 early summer. Tn the course of mv recent tour of investigation 

 through Hamakua to Olaa, T did not find a single example of the 

 short-winged form, while in the winter months from some plan- 

 tations not less than fifty per cent, of the adults sent were of this 

 form. This fact and some observations that I have made on other 

 Hawaiian species, lead me to- believe that the flightless leaf-hop- 

 pers are more prolific than the fully winged specimens. 



