90 WHITE-PINE LEAF-LOUSE 



louse hatched this year at least ten days earlier than usuah But 

 all years are sufficiently hot in mid-summer, and all the stages 

 of these insects are accomplished with great rapidity. By the 

 30th of July many of the eggs of this second brood had hatched, 

 and by the end of the first week of August about half of the eggs 

 under each scale had hatched, and the young had fixed them- 

 selves upon the nearest leaflets, many of them settling upon the 

 same leaflet on which they were hatched. 



And now began to be apparent one of the most remarkable pe- 

 culiarities in the history of these singular insects. Up to this 

 period — about the seventh of August — nearly or quite all the 

 eggs that had hatched, and which appeared to have been that 

 portion of them which had been first deposited, and which conse- 

 quently lay farthest from the insect's body and nearest the end of 

 the scale, had produced only male insects, clearly indicated by 

 the development of the small linear scales. After this period, as 

 the remaining eggs, gradually hatched, a sprinkling of the broad- 

 er female scales began to appear ; a few mingling with the male 

 scales upon the same leaflet on which they had hatched, or the 

 leaflets next adjacent, but the most of them migrating outwards 

 upon the young or terminal whorl of leaves, on which no male in- 

 sect was to be seen. And here remark the wonderful instinct 

 displayed by these creatures, which are usually considered as oc- 

 cupying almost the lowest rank in the insect scale. The males, 

 which will remain attached to the leaf but a short time, and 

 which will soon acquire wings with which to transport themselves 

 whithersoever they desire, attach themselves iudifierently upon 

 the first vacant space they can find, whilst the females, whose 

 power of locomotion is limited to the first two or three data's of 

 their existence, improve this transient period to spread out \jpon 

 the terminal foliage where they will find a fresh supply of n\itri- 

 ment, and in this way each succeeding generation comes into ex- 

 istence where it will find the easiest access to the youngest and 

 freshest foliage. Amongst the many wonderful provisional in- 

 stincts of insects, this is by no means the least remarkable. But 

 wonderful and beautiful as all this is, so far as the insects are con- 

 cerned, it is precisely that course of procedure which is most 

 fatal to the tree. The eggs which produce females, and which, as 

 we have seen, do not begin to hatch till about two weeks later 



