THE GUIDE TO NATURE 



Little Strangers on the Bark. 



BY S. F. AARON, SF.CANE, Dth. CO., PA. 



The big" things in nature instantly 

 attract our attention; we are apt to 

 overlook the many minute though often 

 very beautiful forms of life that are to 



BLACK AND WHITE CREEP1R DISCOVERIN! 

 A COLONY OF BLA«K FLIES. 



be met with everywhere. Of plants 

 and animals it is an interesting thought 

 that the habits, the life histories of the 

 tiny denizens of field and forest are as 

 complete, as complex and perfect as 

 those of the larger and commonly ob- 

 served creatures that we know so well. 

 Between the hummingbird and the 

 eagle there is little to choose in actual 

 interest, the smaller bird has greater 

 problems to face and more difficulties 



to overcome in the struggle for exis- 

 tence. In the insect world there are 

 hosts of tiny beasties well worth spy- 

 ing out for the interest they will in- 

 spire in their perfect and well ordered 

 existences. 



On the bark of trees, particularly on 

 the dead limbs of oaks, beeches, orange 

 and cherry trees and often among the 

 withering" needles of pines and spruces 

 are to be found by a little close obser- 

 vation a group of the most delightfully 

 droll little winged and wingless crea- 

 tures. They remind one of a herd of 

 microscopic and cleanly swine, round- 

 bodied and sleek and often very pig- 

 headed mentally. These are the bark 

 Hies, known to naturalists as the Psoci- 

 dae (do not sound the P.). but the 

 books have little to say about them for 

 the reason that the writers know very 

 little concerning their habits and the 

 varied forms. In one group, to which 

 the very minute book lice belong, the 

 individuals of all ages are without 

 wings. The bark fiies proper consti- 

 tute another grou ) that possesses 

 wings when adult ; the immature 

 stages are wingless but exactly resem- 

 ble their parents in appearance other- 

 wise. The book louse, sometimes very 

 foolishly called "death watch" because 

 of a ticking sound it is supposed to 

 make at night in beds or bedrooms and 

 that may have been heard when per- 

 sons were very ill or dying, is well 

 known and often observed in attics, cel- 

 lars, musty book shelves or collections 

 of natural history specimens. 



The out of doors species, the winged 

 forms, we are most a it to regard with 

 interest. The trolley rider through 

 tree shaded town and citv streets will 

 see upon the white page of book or 

 paper a very small, compact-bodied fly 

 with folded iridescent wings, seeming 

 undetermined regarding the nature of 



