f Book- Lice and Their Allies 



smoky-brown in color, and is seen upon the trunks of trees in 

 flocks numbering from a dozen to forty or fifty individuals. 

 They feed in companies and browse upon the lichens, which they 

 cleanly remove from the bark, leaving a clear space behind them. 

 The colonies consist of one or more families, and include indi- 

 viduals of all ages, the wingless young herding with the adult 

 insects. The adults, although winged, do not readily take flight. 

 When alarmed the whole troop huddles together apparently for 

 mutual protection like sheep, but when seized with a sudden 

 panic they scatter in every direction and run rapidly over the 

 bark, their color harmonizing so closely with that of the bark 

 that they are not easily distinguished. Soon after they reassem- 

 ble and begin to eat the lichens. 



The eggs are oval, glistening white, and are laid upon the 

 bark in batches of fifteen to thirty, deposited on end in several 

 rows, and each cluster is protected by an oval, convex shield of 

 gnawed-up wood which adheres closely to the eggs. The 

 females brood over the eggs, see that they are not disturbed, and, 

 when they hatch, lead the young ones forth to pasture. 



This insect is fond of shade and moisture, and is most often 

 seen in densely shaded groves and old gardens. The adults, 

 according to Hubbard, hibernate, and begin breeding early in the 

 spring. 



Hubbard has also studied another species, Psocns citricola, 

 which is probably a Southern form. With this species the eggs 

 are laid in hollows upon orange leaves in little clusters covered 

 with a shield of black excrementitious matter. Over this is 

 stretched a slight silken web. The embryo is plainly seen 

 through the shell, and when ready to hatch air bubbles are seen 

 which pass in rapid succession between the mouth-parts and 

 collect in a larger bubble within the head. From time to time 

 this larger bubble passes down into the body cavity. The head 

 swells — elongates — distends the eggshell at the end until it bursts, 

 and then the young insect protrudes its body. Air continues to 

 pass through the neck into the abdomen, which becomes greatly 

 distended and elongated, and this distention causes, probably, 

 the bursting of the first larval skin. The process of hatching 

 occupies several days. 



This species lives upon the leaves of plants associated in 

 small flocks, and passes the greater part of its life hiding under 



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