6 
BULLETIN SOS, U. S. DEPARTMENT OF AGRICULTURE. 
practically every wheat-growing section east of the Mississippi 
River, it rarely has caused any serious losses in recent years, al- 
though it exacts a small toll annually. This possibly may be ex- 
plained by the fact that wheat fields in the Eastern States are lo- 
cated usually at a distance from the old stubble fields of the previ- 
ous year, and since the spring generation is wingless, only a small 
percentage of the individuals is able to make the journey safely 
from one wheat field to another, and it thus becomes difficult for the 
species to maintain itself. 
H. grandis is a comparatively old offender, but probably has. 
escaped being confused with other species, as it has some rather 
striking characters, though the fact that it is dimorphic greatly 
perplexed all entomologists for a number of years. Each form was 
considered and described as a separate and distinct species. Riley 
(11) described the spring form as Isosoma tritici 
in 18S2, since he considered Fitch's tritici as a 
synonym of hordei Harris. In 188-i the late F. If. 
TTebster established the dimorphic habits of 
grandis, rearing both forms, and Eiley (12) de- 
scribed the summer form as Isosoma grande. In 
1896 Howard (S. p. 10) definitely established 
Fitch's tritici as a valid species and gave the 
name minutum to the vernal generation of Riley's 
species previously referred to in literature as 
tritici. H. grandis is probably the most inter- 
esting species of the whole group. There is one 
other species that has two generations during the 
year, but no others, so far as is known, are 
dimorphic. 
Fig. 3. — Wheat straw- 
worm : Wingless adult 
female of spring form 
(Harmolita grandis^ 
form m i nut a ) . 
Greatly enlarged. 
(Webster and 
Reeves.) 
HOST PLANTS. 
The writer has never succeeded in rearing H. 
grandis from any plant but wheat. He has 
observed it oviposit in other plants but no larvae were ever found 
in them. Further experiments along this line may disclose other 
hosts. As it is found in sections where very little wheat is grown 
consecutively, it seems as though there must be at least one other 
host. 
LITE HTSTOEY A>TD MAXNEE OF IN.JUEY. 
The spring form (fig. 3) (H. grandis. form minuta) attacks the 
wheat plants when they are small (fig. 4). the eggs (fig. 2. /) being 
deposited in the base of the young plant. The developing larva 
totally destroys the tiller affected, and if the plant has not tillered 
