45 
THE ARMY WORM. 
(Leucania unipuncta Haw.) 
With the rapidly increasing area of low, wet lands, which are being 
under-drained aud brought into cultivation, the natural haunts of this 
species becomes more and more encroached upon. What the ultimate 
effect of this change of natural conditions will amount to in the future, and 
whether or not it will have a tendency to scatter the spring brood of 
moths in their selection of places of oviposition, only future years will 
answer. In accordance with the characteristic partiality of the species 
for low, damp localities, the outbreaks in Indiana this year have been 
restricted to the lower laying and flatter portions of the State, where a 
very considerable part of the land remains undrained, except by open 
ditches. While this state of affairs has been going on, the fact that dry 
seasons are favorable to the increase of the species has been amply 
demonstrated. The last two summers have been unusually dry, and 
the spring of the present year, up to May 30, was exceedingly dry, mak- 
ing three consecutive years of drought, during all of which this pest has 
appeared in various portions of the State, the maximum injury being 
caused the present summer. During this period, also, we have had wet 
springs and dry summers and dry springs and wet summers, proving 
conclusively that wet weather has little if any direct influence upon the 
increase or decrease of numbers. In short, it is difficult to resist the 
suspicion that this ebb and flow, so to speak, may be due more to the 
fluctuation of natural enemies than to the direct influence of meteoro- 
- logical conditions, severe droughts excepted. 
In the vicinity of Princeton, Ind., where considerable damage was 
done last year, there occurred this season only one weak, aborted out- 
break, in a small field of rank growing timothy grass. A slight attack 
three years ago on the borders of a large tract of swampy land in 
the vicinity of La Porte, Ind., was not followed by others, either last 
season or this, although this year similar and more serious outbreaks 
occurred in that immediate section of the State, and within a few miles 
of the same locality. Such phenomena can not be wholly attributed to 
meteorological conditions, most certainly. The most efficient parasites 
of the army-worm are two species of Tachine, and we have reared both 
plentifully this season. The local effects of these parasites is probably 
more lasting than we are given to suppose. <A circumstance came under 
our observation recently where the attack of a similar species of Tachina 
on the larve of Datana ministra, infesting an isolated walnut tree, was 
such that the tree has been free of the caterpillars since 1885. If the ef- 
fects are equally lasting in the case of the army-worm it will be difficult 
to foretell their appearance in dangerous localities, even in seasons sup- 
posed to be most favorable. 
Again, the secret of the power of the army-worm to destroy is in their 
massing together in endless numbers. Were it not for this they would 
