August, '13] TEPPER: YUCCA INSECTS 359 



escape where oil had not been applied. From August 10 to 25, during 

 the August perigee, 2.85 inches of rain fell, an amount ample to pro- 

 vide a brood on its own account. At the time of the first September 

 brood it rained in all 0.95 of an inch, enough to materially increase the 

 size of that brood. All in all, rain-fail conditions in 1912 decidedly 

 favored an abundance of salt marsh mosquitoes about New Haven. 



Investigations along the line of the relations of the tides and rain- 

 fall to breeding of salt marsh mosquitoes are far from complete, and 

 offer an interesting opportunity for the investigator looking for a 

 chance to increase our knowledge of the obscure physical causes 

 which influence the varying abundance of life on our planet. Such 

 an investigation would in the end pass out of the field of the ento- 

 mologist into that of the engineer, or physiographer and the geologist, 

 according as stress was laid on the tides or the marshes, but there 

 is room for much more investigation on the purely entomological side. 



NOTE ON THE FLOWERING AND FRUITBEARING OF 

 YUCCA ALOIFOLIA IN SOUTH AUSTRALIA 



By J. G. O. Tepper, Norwood, South Australia 



Twenty years ago the writer contributed a short note to Insect Life, 

 1892 (Vol. IV, p. 74), when he first observed sound, but then still im- 

 mature fruit at a distance from Adelaide of 30 miles ; this struck me as 

 singular on account of its dependence upon a highly specialized moth, 

 endemic as well, in the American home. Excess of office work pre- 

 vented me from investigating the problem personally as to the polli- 

 nation of the Yucca in this state, there being no plants accessible to 

 me, and the few other South Australian lepidopterologists were prob- 

 ably in a like fix, for nothing so far seems to have been done to discover 

 the insect agent. However, a year or two later I acquired a young 

 shoot of the fruiting species of Yucca, and planted it in my own back 

 garden, where it prospered and grew, but did not flower for many 

 years. 



Three years ago, however, when the tree had attained a height over 

 eight feet, it developed its virginal flower spike, but this set no fruit. 

 Last year (1911), however, it produced two opposite branches near the 

 crown, and both of these developed flower spikes, one a month in ad- 

 vance of the other. Of these, while the earlier one was in flower, but 

 still bore buds, and the later only immature buds, I managed to take 

 a photograph (PI. 8, Fig. 1), December 22, 1911, of the crown with some 

 difficulty. The older spike (right side) remained sterile, although 



