258 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



breed quite continuously under practically all kinds of climatic condi- 

 tions from cool humid to hot arid. The only requisite is that its 

 host-plant shall continue in a condition of normal physiological 

 activity. From this fact much interest, both from a bionomic and 

 from an economic standpoint, attaches to the recent spread of the 

 insect into the coast region of northern Peru. 



The climatic conditions of Piura Department are practically unique. 

 Situated about 5° south of the equator and practically at sea level, 

 it partakes of few conditions that may be considered even tropical 

 not to say equatorial. Probably no other region on earth is. similarly 

 influenced as to climate. So far as rainfall is concerned it is highly 

 arid, being practically rainless, but during at least six months of the 

 year — June to November — its atmosphere is largely charged with 

 humidity. From the latter part of December to the first part of May 

 it is a truly arid and extremely hot region, comparable during these 

 months with the summer season of Sonora, Sinaloa and the Gulf 

 Coast of Lower California. These conditions are due to the trade- 

 winds which sweep tropical South America in a general westerly 

 direction, to the peculiar configuration of the Ancles south of the 

 equator which deflects these winds upward, and to the northward- 

 flowing cold Humboldt ocean-current from the Antarctic region which 

 hugs the west coast of South America until near the equator and sends 

 over the Peruvian coast region an unvarying south wind cold by com- 

 parison in the humid months but tampered by the fierce heat of 

 summer. 



H. minor, having gained access to this region with its peculiar 

 climatic conditions, either brought with it or was met here by certain 

 microhymenopterous parasites common to diaspine scales in tropical 

 and subtropical countries and by some especially American. These 

 parasites are practically confined to the now nearly cosmopolitan 

 Aspidiotiphagus citrinus, Prospaltella aurantii and apparently P. ber- 

 lesei, Aphelinus fuscipennis, and two or three if not more species of the 

 tropical American genus Signiphora. These parasites are very active 

 during the humid months, but unlike the host are unable to continue 

 high activity during the hot dry months of summer. The dry and 

 excessive heat of December and January sends most of them into a 

 state of what I shall term aridation, in contradistinction to aestivation 

 which takes place during the dry season in humid climates but under 

 conditions of considerable atmospheric humidity. The host, being 

 furnished with a never-failing food-supply in the ever-active cotton 

 plant of this region, which affords it moisture internally and externally,^ 

 protected as it is from outside conditions by an impervious scale, is 

 not similarly affected by the change to hot and dry conditions but 

 continues as active as before. 



