26 
We may therefore assume as pretty well established, that the life 
of the individual of the Spring brood from the time the egg is 
deposited until the resulting moth lays her eggs, lasts not less than 
seventy-seven days under ordinary circumstances, with the probability 
that it may be extended rather than shortened. But the length of the 
individual life does not give us the period the brood exists. Prof. 
Ptiley has shown clearly, what is corroborated by the observations 
of others, that the development of different individuals varies con¬ 
siderably, especially in the larval and moth states. 
As all the facts ascertained in reference to the history of the 
species in the northern section of our country (as I have defined 
this term) tend at least to show, if they do not demonstrate posi¬ 
tively, that the species appears in broods, which do not so run into 
each other as to lose this characteristic, that is to say, one brood 
entirely disappears in one state—say for example the larval—before 
it appears again in that state, (though the larva of the second may 
appear before the moths of the first disappear), it is therefore neces¬ 
sary, in order to understand the entire history of the species, to 
determine the length of time a brood exists. Though in calculating 
the possible number of broods we must use the life term of the 
individual. 
The worms first seen were near Murphysboro, in Jackson county, 
Illinois, April 29; were quite small, at most not more than one week 
old. This would make the date of hatching about April 2'. The 
last seen went into the ground about June 10th. Allowing one 
month for the larval life, this would show a variation of eighteen 
days. 
Col. B. L. Wiley, of our county, who has observed this insect very 
closely during the past thirty years, gives forty days as the term of 
existence, as worms, from the time first seen- very young—until all 
have disappeared. Supposing them to be a week old when first 
observed—and from his description they could not have been older— 
this gives a variation of seventeen days. Prof. Ptiley’s statements, 
“during the latter part of April” and “early in June,” will give at 
least as great variation as above shown. Lintner’s list of moth 
captures indicates that the moth lives considerably longer than the 
larva, or that the variation in the time of appearing is much greater 
than shown above. The variations in the specimens reared by Mr. 
Goodale (reported by Dr. Packard) amounted to nine days only. 
It Avill probably be safe to assume at least eighteen or twenty 
days as the difference in the time of appearing and disappearing of 
the different individuals of the spring brood. Add this to the life 
of the individual and we get from ninety-five to ninety-seven days 
as the brood period from the first eggs until eggs are again all 
deposited. If we take Lintner’s list and calculate back to the time 
the egg was deposited which produced the moth caught August 7tli, 
and forward from that time to October 6th, we have (supposing the 
moths then ceased to exist) as the entire life of the brood from the 
first egg to the death of the last moth one hundred and twenty-two 
days. This estimate is of but little value, as it is possible the moths 
or a portion of them live through the winter. The life of the indi¬ 
vidual is therefore the only safe guide in discussing the question 
