234 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



the removal of this growth. Generally speaking, grass is more abund- 

 ant in fields of young plant cane and this may have some connec- 

 tion with the attack on the cane. Larvae may also invade cane fields 

 from adjoining grass areas, especially when the food supply becomes 

 exhausted. 



The larvse apparently prefer the young cane. Mr. Van Dine states 

 that the severe injury following heavy rains at Buena Vista was con- 

 fined to the young cane, there being no apparent injury to the more 

 mature cane growing on land that had also been under water. At 

 Mameyes the young cane had apparently been preferred to the older 

 growth. This may be because the larvae do not naturally seek the 

 higher plants. Tn an extensive article on this insect, published in 

 1901, Dr. F. H. Chittenden states, " — these larvse prefer low growing 

 plants."! 



There have been remarkably small second broods of larva? in locali- 

 ties where outbreaks of "grass worms" occurred. At Rio Piedras, 

 although moths from the larvae of the destructive brood were seen to 

 issue in some numbers, the second brood of larvae was of small conse- 

 quence. Neither were there any reports of abundant second broods 

 at other points on the island where similar outbreaks had occurred. 

 This decrease in numbers can be accounted for, in part, by the presence 

 of parasites and predaceous enemies, and cannibalism may play an 

 important part in the reduction of the species on areas where the 

 supply of vegetable food becomes exhausted. One case of cannibalism 

 was noted in the field a,t Rio Piedras, one Laphygma larva being seen 

 to grasp another and soon disembowel it, both specimens being on 

 the surface of the soil at the time and the attacked larva apparently 

 about to molt. It is also possible that the moths, on issuing, may 

 fly to a considerable distance before depositing their eggs, the result 

 being that the larvse of the second brood are scattered over a larger 

 area and the results of their feeding not so apparent. 



Life History. On April 27, 1912, the writer found a cluster of 

 forty-six eggs of Laphygma frugiperda on the upper surface of a leaf of 

 young plant cane at Rio Piedras. The eggs hatched on April 30 and 

 eight of the newlj^ hatched larvae were placed in separate glass vials, 

 plugged with cotton and containing leaves of "malojillo." The re- 

 mainder were placed in a battery jar containing moist earth and "mal- 

 ojillo." The contents of the vials were examined from day to day, the 

 grass and excreta being removed and fresh grass introduced. As the 

 larvae approached maturity they were transferred to glass bottles con- 

 taining moist earth; leaves of "malojillo" still being given as food. 

 The larvae in the battery jar were not as closely watched, though they 



iBuUetin 29, new series, U. S. Dept. of Agric, Div. of Ent., p. 31. 



