OF LANCASTER COL'NTV. 521 



ORDER AMPJnroJjA. 

 This order contains the "water-doa.s,- ..l" whicli there are a numl.er ..f .s,K.nu.s hut 

 their description and names, if they have ever heen descrihed and named, are not 

 accessible to me, and therefore tliey are necessarily omitted. Tlu-sr animals are found 

 in great abundance upon the bottoms of all our sprini,^s and rnnniu;,^ streams. The 

 most common species is Asellus aquitiici/:^. 



ENTOMOLOGY.! 



The subject of Entomology cannot be so localized as to include only the in.sects of a 

 single county; and therefore all, or nearly all, of that class of animals, alluded to in 

 this 'paper, will also be found in the counties of York, Chester. Beiks, Lelianon and 

 Dauphin; territory that environs Lancaster county; and possildy it may include all 

 that inhabit the same belt of latitude, through the State of Pennsylvania — at least in 

 that portion of the aforesaid belt, that is of the same degree of elevation or altitude. 

 There is, however, within the territorial limits of the State of Pemisylvania a marked 

 distinction in the local distribution of insects, the Southern tier of counties i)rodueing 

 those that are also common to the Northern tiers of Maryland and ^'irginia; and the 

 Northern tier those that are common to the Southern portions of the State of New 

 York. Still, there are many species that are common to the entire territory of the States 

 named, and some common to the whole United States. Under any circumstances, we may 

 infer that the local distribution of the entomological fauna of a country, or any part 

 of a country, will be more less in correspondence with the local distribution of its dora; so 

 far at least, as the subjects of the former are dependent upon the latter for their nonnal 

 food. In.sects, moreover, in some instances, become localized through civilization and 

 commercial intercourse. A numljer of the wood-boring beetles conunon to the wild pine 

 regions of Pennsylvania — in the North — have l)ecome localized in the county of Lan- 

 caster; having been brought down the Susquehanna river, in the larva, or the pupa 

 state, in sticks of timber, or sawed lumber; and then, having betaken themselves to 

 similar trees or timber, in their new locality, have become permanently established. 



Nor can the subject be so particularized as to contain a detailed description of the 

 various species that are found in the county and adjacent territory, nor to include 

 a complete catalogue of them. Because, to do the former would involve the ])roduc- 

 tion of a book quite as large as the whole history of Lancaster county is propo.sed to 

 be; and to do the latter, would only be enlarging a list of Latin names, that are per- 

 haps of very little interest to the general reader. Under any circumstances it will 

 be utterly impossible for the most careful observer to form a proper conce])tion of 

 the denizens of the insect realm, without considering them as a whole as well as si)ecili- 

 cally, and noting the transformations of the various individuals composing tiiat realm, 

 from the ova to the larvce and their moultings, and thence through thcii pupal changes, 

 until they arrive at tlie full and perfect development of the matured tmac/o. Insects 

 difter so much in their habits, and are so diverse in their structure and form, during 

 these periods, that, without the most careful ob.servation, they are liable to be mistaken 

 in their specific relations, and their individual identities. Wliatever may have been 

 the origin of insects in the beginning, or whatever may be their origin now or liereafter, 

 under extraordinary circumstances, it is pretty well established that their ordinary 

 production is from eggs, deposited by a female parent; except in a few instances, 

 where they are viviparous. The fir.st recognizable state of the insect then, is the ociim 

 or egg. Incubation may take place in a few days after deposition, or it may be defer- 

 red, through the rigor of an intervening winter, to another season. The eggs are 

 usually deposited in such situatioms, and the exclusion of the young occurs at such 

 1 Contributed by Jlr. S. S. Rathvon. 



