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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
first newly transformed adults were secured on July 5. Headlee and 
McColloch 1 state that at Manhattan, Kansas, in 1912, the first fourth 
instar nymphs were obtained on June 4 and were at their maximum 
abundance on June 30; that the first newly transformed adults were 
taken on June 14 and were at their maximum on July 10. 
In Montana fourth instar nymphs were at their maximum abun¬ 
dance in 1911 as early as May 23, and probably on April 15. Newly 
transformed adults were abundant on June 12, and in 1914 several 
were secured on June 4. It does not seem possible that the seasonal 
history of the chinch bug in Montana could be a month earlier than in 
Kansas and Missouri, which are 10 degrees further south and the only 
reasonable explanation of the appearance of fourth instar nymphs in 
April and May is to assume that they hibernate in that stage. 
This assumption is further strengthened by Hopkin’s law of latitude, 
longitude and altitude 2 which states that the variation on the date of a 
periodical event in the seasonal activities of a plant or animal is at the 
average rate of four days for one degree of latitude, 5 degrees of longi¬ 
tude, or 400 feet of altitude. Glasgow is 10 degrees north and 10 
degrees west of Manhattan, Kansas, and is about 800 feet higher. 
Applying Hopkin’s law to the statement of Headlee and McColloch, 
that fourth instar nymphs are at their maximum abundance on June 
30 at Manhattan, Kansas, we would not expect to find them in abun¬ 
dance at Glasgow until 38 days later, or July 8. Instead of this we 
find them in abundance on May 23 and reported in abundance as early 
as April 15. It therefore seems impossible that these nymphs could 
have developed from eggs laid that same season. 
Perhaps no definite statement should be made until we find the 
chinch bug in its winter quarters, but the above data, together with 
the fact that adults, which emerged in the insectary on June 12, pro¬ 
duced progeny which failed to mature that season, indicates that in 
Montana the chinch bug changes its usual habit and hibernates as a 
well advanced nymph. 
Host Plants 
In the Glasgow district chinch bugs were first noticed in a field of 
oats which was said to be swarming with nymphs in May and the 
owner was very positive in his statement that many of the young 
plants had been killed. Chinch bugs were also found in June upon 
wheat and corn, but as far as could be learned no serious injury 
occurred. 
Chinch bugs occurred most abundantly upon the native grasses. 
1 Kansas Agricultural Experiment Station, Bulletin 191, page 303. 
2 Jour, of Econ. Ent., Vol. 10, No. 1, page 160. 
