53 



Washington is situated well within the Carolinian area of the Upper 

 Austral life zone, but collectors who have given the study of the dis 

 tribution of animals any attention are aware that the insect fauna of 

 the northern portion of the Carolinian and that of the southern portion 

 of the same life area differ to a very considerable extent. Although 

 many species are common to both regions, certain forms will be much 

 more abundant either in the northern or in the southern extremities. 

 In other words, there are present in the southern end many forms which 

 properly belong* to the Austroriparian section of the Lower Austral, 

 while the northern portion has a preponderance of Transition or Alle- 

 ghanian species. 



The District of Columbia occupies a place in the Carolinian fauual 

 area about midway between the two extremities. Many of the north- 

 ern or Alleghanian species are rarely met with in numbers save in 

 exceptionally favorable seasons, likethat of 1899, while the southern or 

 Austroriparian forms which inhabit this latitude are usually to be 

 found in all years. 



SOUTHERN CHARACTER OF THE INSECT FAUNA OF THE DISTRICT 



OF COLUMBIA. 



In the Heteroptera we find perhaps the most noticeable examples 

 from the southern life zones. A very considerable number of large 

 conspicuous southern species 1 habitually occur here, and their usual 

 normal northern limit is not far north of here in Maryland, except near 

 the coast line, where many species of this, as well as of other orders, 

 go considerably farther north than they do inland, some extending into 

 southern Xew Jersey and parts of Pennsylvania, and a few following 

 the coast to the shores of Long Island. 



A notable feature in connection with the occurrence of the northern 

 species of Coleoptera in this vicinity is that they are mostly vernal, 

 appearing late in March or early in April if the season favors or in just 

 about the same temperature which induces them to issue from their 

 winter quarters a month and more later in their more northern habitat. 2 

 Injurious species which appear at this time include the white-pine 

 weevil (Pissodes strobi), certain other weevils and Scolytids which infest 



1 Among these species may be mentioned: Leptoglossus corculus, Metapodius termi- 

 nalis, Arcliimerus calcarator, Euthoctha galeator, Ectrichodia cruciata, Chariestents an- 

 tennator, Stenopoda cuUmformis, Xarvesus carolinensis, Pnirontis inftrma, Pygolampis 

 pectoralis, and Largus ductus, many of which are usually abundant. Of rarer but 

 conspicuous species occasionally taken here are Sirthenea carinata and Tetyra bi- 

 punctata. The former has been taken only at light; the latter on Pin us inops early 

 in spring. 



2 Many Lower Austral forms which have become injurious in this region are on 

 the other hand remarkably late in their occurrence in the field, some of them produc- 

 ing an extra generation here after the native species have gone into hibernation. 



