236 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



The season preceding the outbreak in 1890 was one which would have 

 grown volunteer wheat and oats throughout the summer in the section 

 of the country where the Toxoptera were abundant. Furthermore, it 

 appears that the winter of 1889-1890 was of a mild type, especially in 

 southern Ohio, southern Illinois, southern Missouri, and Texas. The 

 spring of 1890 opened quite early and warm, but later changed to cold, 

 raw weather, which continued up until the latter part of Maj'. These 

 conditions are readily comparable to the weather conditions of the 

 spring of 1907 and the spring of 1916. 



The outbreak of 1901 seemed to be confined mostly to northern Texas. 

 By consulting the weather records, we find that in 1900, August, Sep- 

 tember, October, and November were very rainy months. This, of 

 course, afforded an abundance of volunteer oats and wheat. March of 

 1901 opened up with showers and rains, which continued into April, 

 with the weather turning cool with near frosts in April. The rains 

 during the month of May were very light and a drouthy condition ex- 

 isted in north central Texas. It will be seen here that we have a condi- 

 tion very similar to that of 1889 and 1890. 



Continuing our investigations, then, to 1906, we find that during the 

 summer and fall the weather conditions were favorable for the growth 

 of volunteer grain from central Texas to Nebraska, that is, rainfall was 

 well distributed throughout July, August, and September. There are 

 no records on file as to the amount of volunteer grain. However, our 

 more recent investigations lead us to assume that there was plenty of 

 volunteer grain where the rainfall was as abundant as in this season. 

 The following winter was very mild. The spring of 1907 opened early 

 and with slight rains in March and April, but here the weather man got 

 his calendar mixed and we had it very cool in April and May, continu- 

 ing cool up until late May. This insect, therefore, had the most favor- 

 able opportunities for increase. 



In 1908, following the severe outbreak of 1907, a small area of wheat 

 and oats in northern Kansas was damaged, this outbreak being evi- 

 dently continued from the outbreak of the spring of 1907. Investiga- 

 tion indicated that the insect had been present in the infested fields 

 since the spring of 1907, at which time the entire country to the south 

 was being devastated, also that the devastated wheat fields had been 

 planted to oats, and that occasional rains in July, August, and Sep- 

 tember had kept the oat plants suckering and green throughout the 

 summer, and with the volunteer crop coming early in July, the aphids 

 were permitted to feed and breed freely in the field, until wheat was 

 sown. Shortly after the wheat was sown, the frosts killed down the 

 oat plant, thus precipitating the Toxoptera on to the wheat; it, being 

 young, of course succumbed readily. The devastation was not very 



