93 



GRAIN INSECTS. 



The southern grain louse (Toxoptera graminum RoncL), made its 

 appearance on wheat and oats in parts of north Texas early in March, 

 but was soon destroyed by parasites. The winged aphis evidently 

 migrates to the grain in the fall, as the injury commences in spots 

 here and there over the field, and previous to the outbreak of 1901 

 these spots were observed as early as December, 1900. It seems prob- 

 able that the pest is held in control by hymenopterous parasites whose 

 reproduction is prevented by continued cold, wet weather, as Pro- 

 fessor Webster has shown is the case with the nearly allied grain 

 ISTectarophora. The earl} 7 spring of 1901 was unusually cold, wet, and 

 backward in the injured territory. The aphides disappeared from 

 the fields early in April, 1903, as in 1901. Evidently they migrate to 

 some other host plant. They were reared in the laboratory until 

 June 1 without any change of form or habit being indicated. 



Specimens of Nectar oplior a cerealis a were secured early in January 

 and reared until late April. Late in April apterous oviparous 

 females and winged males appeared, and eggs were laid on the stalks 

 of grain in the tubes. I was unable to secure the hatching of any of 

 these eggs, or to find them in the field. This species becomes rare 

 on small grains after early June, when they commence to head. It 

 evidently must migrate to some other plant, upon which it probably 

 lays an egg, as I have been unable to find any record of the egg. 



Aphis avena? Fab, (?) — Specimens determined by Mr. Th. Pergande 

 as this species were found on small grains early in January com- 

 monly throughout the grain belt of the State and sometimes in con- 

 siderable numbers. Several generations were reared up to June 1. 

 This species remains near the surface of the soil, largely at the 

 bases of the leaves. In May it was found on the roots of John- 

 son grass, and it was often found on the crown of a grain plant. The 

 specimens I have do not agree with the description of Fabricius, but 

 are given under this species upon Mr. Pergande's authority. 



Aphis maidis Fitch was received upon barley which it had damaged 

 in January and May. I have not noticed it on an} 7 other small grain. 

 In August it becomes abundant on corn and later on sorghum, some- 

 times doing considerable damage. 



The chinch bug (Blissus leucopterus) has been the most serious 

 insect pest of corn in Oklahoma and north Texas for man} 7 years. 

 In 1901 and 1902 drought and chinch bugs caused a practically total 

 failure of the corn crop in the larger part of north Texas. This year 

 the bugs appeared in large numbers upon the corn as soon as it 



«I am unable to determine whether this is N. cerealis Kalt. or N. granaria Kby. 

 Mr. Pergande informs me that he will shortly publish a paper in which these 

 characters will be defined. Up to this time the two names seem to have been 

 used synonymously by American writers. 



