65 
The winters of 1861 and 1862, the years of the serious outbreaks 
in New York and New England, though not particularly severe in the 
sections above mentioned, were by no means noted for mildness. It 
seems doubtful, therefore, if the causes leading to the invasion of the 
present year would carry us farther back than the spring months, a 
statement strongly substantiated by our own observation. 
Starting, then, with the month of March we search for some meteoro- 
logical element which might affect the increase of the Grain Aphis, and 
which appears both in the present season and also in 1861 and 1862. 
TABLE H.—General weather conditions in various localities during years of great abun- 
dance of Grain Aphis. 
Locality. Year. | March. April. May. June. 
(1861... § Cool... Cool .---.. Cook Fone Goal. 
eg ee Ny Marland oe Peen eos 1969, .|$ Coots -.! Cool 222222) Cook 222222] Goal 
| Wiet 242% 1 Wietsoses. Dryeeeeene dry 
Tnddiana 2-22. 2 see ees ce eeeseeeseeeeee eens PSU one oe ey tbey ee 
DYPSTELTe NCW.) VOLK Seems ae eles sane eal» IEE) 2 c|ladcnetacsbaclloanncecasaoa|laocessans = Wet 
L 
The weather conditions as s relating to New York and New England 
for 1861 and 1862, as given in Table H are based upon reports contained 
in the Country Gentleman for these years. Those for Indiana are based 
on the reports of the State Weather Service, and the data for western 
New York, for 1889, was given me by Prof. James Troop, Horticultural- 
ist of the Indiana Experiment Station, who visited Livingston County 
in July. | 
From Table I, taken from Indiana Weather Service reports, it will be 
observed that during March and April the temperature was considera- 
bly above the normal, with the precipitation during this time below the 
average. On the other hand, the temperature of the months of May 
and June was much below the normal, with, as indicated by Table I, pre- 
cipitation above the average. By referring to Table K, however, it will 
be observed that about half of the precipitation of May fell on the 29th 
and 30th of the month, thereby changing the apparent state of affairs, 
and practically become May into the an period. 
We have stated that the outbreak of the grain Aphis became con- 
spicuous in southern Indiana and Illinois in May. It is also true that 
they reached their maximum numbers during the very last of this month 
and early June. In other words, they appeared during cool, dry weather, 
and disappeared in cool, wet weather. Thus far the old theory of ento- 
mologists, that wet weather is detrimental to their increase appeared 
true. 
But it is also true, that while in southern localities they were disap- 
pearing during a wet period, in central and northern Indiana and 
western New York they were rapidly gaining in numbers, under pre- 
cisely similar conditions. 
23479—No. 22 5 
