LIFE-HISTORY AND HABITS OF TERRESTRIAL ISOPODA 301 



life, and often these mean hours, days, and even weeks of 

 careful and patient study and close observation, before we 

 can rightly interpret the ways and doings of the animals 

 under consideration. 



Many of the habits of woodlice are exceedingly difficult 

 to understand, and only continued observation will help us 

 to glean any information. In some cases a species will 

 remain hours and even days apparently motionless, or will 

 change its position with remarkable regularity, spending one 

 portion of the day at one side of the celP and another at the 

 other side, without apparently any reason. Provided there 

 is a sufficient supply of moisture present, they are capable 

 of living a considerable time without food or on a very scant 

 supply. 



It has been suggested to me, so few are the recorded 

 observations upon their life-histories and habits, that the 

 following ones are worthy of being placed on record. 



Habitat. — Woodlice are only found where moisture 

 exists, in dark and damp situations in the vicinity of dwelling- 

 houses, such as cellars, outhouses, conservatories ; around 

 walls, cisterns, water-barrels, rockeries ; under boards, stones, 

 and rubbish they are commonest. They also occur beneath 

 the bark of dead and decaying trees, amongst decaying 

 vegetable matter, in manure heaps, under moss, stones, 

 seaweed, etc. Some species occur only close to the 

 sea, whilst others are common in the open fields, on 

 moorlands, etc. 



Moisture being the prime requisite to their well-being, 

 wet seasons are exceedingly favourable to a rapid increase 

 in their numbers. 



Reproduction. — Pairing takes place early in the spring, 

 during April and May, and the eggs are retained by the 

 female in the brood-pouch for a varying period. The 

 number of young produced also varies greatly. Examples 

 of Porcellio scaber, Latr., which I have kept in captivity for 

 some time had broods of twelve to thirty young. For 

 Armadillidiwn vulgare, Latr., the numbers varied from 

 thirty to sixty, and in Oniscus asellus, Linn., I have counted 



^ See p. 306. 



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