12 DEPAETMENT BULLETIN 1267, U. S. DEPT. OP AGRICULTURE 



may be toxic for them. This view is supported by results of field 

 observations, which show that larvae of this species are only very 

 exceptionally associated with manure. Thus in the old pasture at 

 Tappahannock, where the larvae were abundant, they were never 

 found beneath the droppings of cattle, although repeated search was 

 made for them in such locations. Furthermore, they were no more 

 frequent in fields that had been treated with manure than in those 

 that had been left untreated. The junior writer has repeatedly 

 searched for the larvae in fields to which manure had been added 

 earlier in the season, but although the larvae of certain other scara- 

 baeids, such as Ligyrus gibbosus (De G.), Dyscinetus trachypygus 

 (Burm.), and Cotinis nitida (L.), were unusually common in such 

 fields, those of Euetheola rugiceps were either entirely lacking or 

 extremely scarce. 



Whether, under natural conditions, the larvae ever subsist upon 

 living plant material is a question which can not as yet be answered. 

 From the fact that the older larvae in the breeding experiments were 

 fed with kernels of corn, it would not be unreasonable to suppose 

 that they may feed to some extent upon living plant material. The 

 frequent association of the larvae with grasses of the genus Paspalum 

 suggests the possibility that they may feed upon the rootlets of these 

 plants, though it is also possible that this association is purely acci- 

 dental — a result of the parent beetles depositing their eggs in such 

 spots while feeding upon the plants. 



Howard (7) and Titus (13) have inferred that the larvae feed 

 upon the dead and dying roots of the kinds of cultivated plants — 

 sugar cane and corn — destroyed by the adult beetles. Titus, indeed, 

 goes so far as to offer the suggestion that the object of the beetles in 

 attacking sugar cane is less to secure food than to provide a supply 

 of dead and decaying vegetation for the larvae to feed upon. So far 

 as corn is concerned, however, there can be little doubt that the 

 beetles attack it primarily for food, and that if the destruction caused 

 thereby is of benefit to the larvae it must be a very indirect benefit. 

 The junior writer has tested the capacity of the very young larvae to 

 feed upon dead and decaying corn rootlets, and, while the experi- 

 ments were not sufficiently extensive to settle the matter fully, the 

 results were entirely negative. 



It has been suggested that the larvae may feed in decaying wood, 

 as do those of some of the near allies of this species. Examination 

 of old logs and stumps at Tappahannock for larvae of Euetheola 

 yielded only negative results, and it seems reasonably certain that 

 they do not occur in such situations. 



In the experiments at Charlottesville an effort was made to rear 

 the larvae from forest leaf -mold, but, although they appeared to eat 

 this, only a very small proportion of the larvae tested lived beyond 

 the earliest stages. There is no evidence that the larvae ever feed 

 upon such material under natural conditions. All attempts to find 

 the species in timbered areas were unsuccessful. It is apparently 

 limited to open situations. 



GROWTH 



The larva on hatching from the egg is approximately 3 milli- 

 meters long; when fully grown the length is about 32 millimeters 

 (l| inches). Growth is rapid, the larva attaining full size in from 



