420 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
to these co-workers, many of whom have not been mentioned and due 
credit given in this brief account, to continue the work on forest insects 
so well begun by Dr. Hopkins and we hope that in his newer field Dr. 
Hopkins will meet with the same success that attended his efforts in 
Forest Entomology! 
Thos. E. Snyder, Entomologist. 
William Middleton Assistant Entomologist. 
F. P. Keen, Assistant Entomologist. 
Washington, D. C., August 28, 1923. 
SEASONAL ADAPTATION OF A NORTHERN HEMISPHERE 
INSECT TO THE SOUTHERN HEMISPHERE 
By John C. Hamlin, Officer-in-Charge Prickly-pear Investigations , Commonwealth 
Prickly-pear Board 
Abstract 
Melitara junctolineella Hulst (Order Lepidoptera, Family Pyralidae), one of the 
several insects introduced into Australia in connection with the attempt biologically 
to control the prickly-pear pest, is indigenous to North America. In southern Texas 
it produces two generations annually. Its brood adjustment to seasons was upset 
by departure from our winter and immediate entry into the summer of the Southern 
Hemisphere. During the period it has been accomplishing its swing-over to the 
opposite seasons of Australia three generations have been produced in sixteen months. 
Complete adjustment to the Australian seasons has not yet obtained but observations 
indicate that in its ultimate adaptation to the opposite seasons it will have three broods 
yearly. 
On the one hand it is common knowledge that certain species of 
insects have more or less broods per year as the summer is longer or 
shorter. On the contrary there is evidence to show that certain species 
cease activities at certain periods regardless of the conditions of temper¬ 
ature and moisture to which they may be subjected. These instances, 
however, apply to insects living on the one or the other side of the 
equator. 
When first entering upon duty for the Australian Commonwealth 
Government, I made many conjectures as to the manner in which certain 
species from the Northern Hemisphere would adjust themselves to the 
opposite seasons of the Southern Hemisphere; that is to say where 
summer is simultaneous with our winter. This adjustment has been 
kept in mind, and at the present time it is possible to present preliminary 
data on a yet unsettled adaptation. 
The species in point is Melitara junctolineella Hulst, 1 an insect in¬ 
digenous to North America. The larvae feed within the thick joints 
1 Order Lepidoptera , Family Pyralidae. 
