Sept. 15, 1925 
Reaction of Grasses to Ghinch-Bug Attack 
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insects. Many of the different grasses soon were killed or severely 
injured, while others showed varying degrees of resistance. Notes 
' regarding these differences were taken on July 8. Since such data, 
at best, can be only relative, it was thought advisable to list the 
degree of injury in as few categories as possible. Accordingly the 
following degrees of injury were considered. If a row of grass was 
entirely dead it was noted as killed; more than half dead was con¬ 
sidered severe; if only half dead it was regarded as moderate; and 
when only a few plants were injured it was listed as slight. 
PERCENTAGE OF RECOVERY 
The observations on the ability of the various species of grasses 
to recover from injury were made on August 18. Very favorable 
* growing weather had prevailed between this date and the time when 
the insects attacked the plants. By this date, also, most of the chinch 
bugs had become mature and had flown to neighboring corn and 
sorghum fields. 
In estimating the percentage of recovery, rows in which no live 
plants were present were listed as zero, meaning no recovery; those 
in which only one or two plants were alive were marked 1 per cent, 
and so on, until those rows in which there seemed to be complete 
recovery were noted as 100 per cent. Recovery data for the few 
rows in which there was no injury are not given in Table I. 
PRESENTATION OF DATA 
To the data on the amount of injury and the degree of recovery 
have been added the morphological and ecological features of the 
various grasses discussed in the previous paragraphs and these have 
been summarized in Table I. 
DISCUSSION 
From Table I it seems strikingly apparent that the character of the 
vegetation and the circumstance of whether the species of grass is 
native or introduced, have considerable to do with the ability of the 
plant to withstand chinch-bug attacks. Those grasses having harsh 
tissues seem, in most cases, to be especially resistant, if they are 
native grasses. For example, such a plant as Andropogon scoparious 
(row 3) has harsh tissues and is a native perennial. It is well known 
that it affords the chinch bug protection during the winter, and, in 
the case noted, no injury was apparent, although the plants were 
literally covered with chinch bugs. In the majority of instances of 
those grasses termed “ harsh” in which chinch-bug injury was severe 
and recovery poor, the species were introduced ones. 
It will be observed further that those grasses listed as “inter¬ 
mediate” in regard to their vegetative characters showed varying 
degrees of resistance. Some, sucn as Festuca ovina (row 99), showed 
only slight injury, and with marked ability to recover. Others, like 
Bromus secalinus (row 57), showed only moderate injury and mediocre 
ability to recover. Still others were severely damaged, e. g., Elymus 
glaucus (row 13), and were unable to recover. 
Ubrary 
INVEs TI6AT10h S: 
