372 



I 



without. I have fully verified Trelease's statements by dissectiou and 

 study of the insects seeking this scant nectar, and indorse his conclu- 

 sion that while the observations serve to disprove any positive value of 

 their nectar in the pollination of Yucca flowers, they add to the impor- 

 tance of Prouuba by showing that the acts of collecting the pollen and 

 transferring it to the stigma are performed voluntarily and without food 

 compensation as I was at first inclined to believe 



I have lately had the pleasure of studying Yucca ichipplei in Cali- 

 fornia and the remarkable Tree-yucca ( Y. brevifolia) in the Mojave desert. 

 The former is pollinized by Pronuha maculata Riley, and the latter by 

 a most remarkably modified and adapted species wbich I expect to de- 

 scribe as Froniiha paradoxa. 



Thus everywhere in the United States where Yucca nominally fruits 

 we find it associated with its Pronuba. ' 



I await with interest and curiosity any new discoveries in this con- 

 nection, but, so far as present knowledge justifies anticipation, I should 

 expect, where neither Pronuba nor Pronuba-like insect exists, to find 

 the plant modified to more readily permit self-fertilization sooner than 

 to find Apis melUfica tiie poUiniziug agent, the oi^inion of Mr. E. L. 

 Layard, of Kew Caledonia (who first expressed it in 1880 — Kaiure^ Vol. 

 XXII, p. 606), and of Mr. Hulst, to the contrary notwithstanding. 

 [Reprinted from Proceedings Entomological Society of Washington. Vol. 

 J, No. 3, 2>P- 150-154, read June 5, 1888.] 



NOTES ON SOME SPECIES OF INSECTS WHICH AFFECT THE UP- 

 PER PORTION OF TEE STEMS OF SOME GRASSES, 



Bv F. M. Webster. 



I 



There are several species among our common grasses which are more || 

 or less subject to injury at or near the upper joint, whereby that portion 

 of the culm above is so injured that it will suddenly wither, turn yellow, 

 and die, leaving the portion below this upper joint green and vigorous. 

 Of the grasses thus affected that have come under my own observation, 

 those most commonly injured are Blue-grass {Poa ^;rrtfe?is?\9), Timothy 

 {Plileum pratense)^ Bottle-Grass {Setaria glauca), and Panic Grass {Pan- 

 iciiin crus-galli). 



The extent to which Blue-grass is subject to this attack in the United 

 States, east of the Mississiixi)i and north of the Oliio Eivers, has at- 

 tracted considerable attention, as it has also in Canada. 



In his Third report as State Entomologist of New York, page 96, Pro- 

 fessor Lintner calls attention to the fact that similar injury to this grass 

 was observed long ago and recorded in the Quarterly Journal of Agri- 

 culture and Science, 1, 1845, page 263. Professor Lintner in this notice 



