A stuclv of this table brings out clearly one very instructive fact, 
and hints at several others. We have, in these root-worms, three 
closely related species, attacking the same part of the same plant 
in precisely the same way, at the same stage m their development, j: 
and strictly dependent upon this plant, as far as is known, lor then 
continued existence. One would say that here were all the con¬ 
ditions of a most determined struggle for existence between these i 
three species, in which one or more of them must succumb, it is v 
indeed interesting to see how this issue is evaded, and an adjust- l 
ment reached by which competition is reduced to a minimum. The J 
Oolaspis larva makes the earliest attack upon the plant, beginning its | 
work upon the roots certainly as early as the first of May (half- J 
grown individuals having been taken on the 15th), and finishing m 
June, all being full-grown and preparing to pupate by the end of r 
that month. Next comes Paria, in July and August, neither ex- J 
treme of its period being exactly defined by our observations ; and p 
finally comes Scelodonta, adults of which were copulating July 1, 
young larvae occurring August 7. As far as now known, the bcelo- j 
donta larva is left in undisturbed possession during the remainder f 
of the year, although there is a break in our observations during 
October. Certainly by November it has completed its work, and i 
retired, full-grown and ready to transform, into its subterranean cell. 
It seems clear, furthermore, that this curious succession of periods | 
is related to a difference of habit with respect to hibernation. Un- ^ 
doubtedly, Scelodonta winters as a larva; and Paria as an adult, | 
As Colaspis larvae were only half-grown May 15tli, they very probably | 
hatched from the egg that spring; and as the adult Colaspis emerged I 
' about two months before the new brood of Paria, it seems hardly r 
possible that both could have developed from eggs laid that spring. 
It is much more likely that Colaspis hibernates in the egg. On tins F 
hypothesis, we shall have the eggs of Colaspis deposited in autumn, l 
those of Paria in spring, and those of Scelodonta in midsummer; | 
the first genus hibernating in the egg, the second as an adult, ana, 
the third as full-grown larva, with the necessary result that their , 
attacks upon their common food-plant are delivered successively. 
The advantage of this arrangement is evident where we reflect that: 
by this means as many of each species are fed upon the strawberry 
as it would be possible to maintain of all three if they came inter 
simultaneous competition. 
As a general rule, only the surplus structures of a plant may be■ 
destroyed by insects, since habitually to destroy more, would, m the j 
natural order, eventually exterminate the plant, and with it the id- ^ 
sect itself. As the strawberry plant grows continuously throughou j 
the season, such an available surplus of root growth is continuous yj 
produced, but if all the root-worms were to attack it together, thejjt 
would be limited to the surplus produced during one or two months u 
whereas by distributing their periods of activity, they are able y 
appropriate the whole, and avoid conflict altogether. 
The fact is worthy of notice that the times of the appearance o i 
the adult beetles are not as widely separated as the periods oi 
val activity, the interval from the commencement of the aa 
