54 



conifers, Orsodachna atra, Crepidodera helxines, and other species which 

 are associated with willow. 1 



The other orders of insects doubtless present equally striking exam- 

 ples of the preponderance of southern forms here, but they have not 

 been very closely studied by the writer, and enough has been said to 

 show tbat the fauna is in the main southern. 



EFFECT OF THE COLD WINTER OF 1898-99. 



During the season of 1899 the writer was impressed quite early in 

 the year with the unusual scarcity of certain species which we know 

 are more abundant in the South, and which for the most part have 

 been introduced from warmer districts, and the corresponding abun- 

 dance of many species which, though not peculiar to the North, are 

 more thoroughly acclimated there, and are usually more abundant and 

 destructive in colder climates. This was particularly noticeable of the 

 species which affect garden crops, a group of insects which has 

 engaged the attention of the writer in recent years. 



The cause of this was not far to seek. The blizzard which began 

 February 5 was one of the greatest severity, and the weather was the 

 coldest that has been experienced for more than twenty years. 2 



The winter as a whole was an unusually cold one, with few warm 

 spells, and it was a long time after the blizzard before warm weather 

 was experienced. 15 



These conditions would be conducive to the perfect hibernation of 

 Northern species, but would be destructive to Southern ones. A few of 

 the best observed examples of the effects of the cold winter weather of 

 1898-99 will be given, beginning with a consideration of Southern forms. 4 



1 Among conspicuous southern species of Coleoptera occurring near Washington 

 are: Helluomorpha bicolor and nigripennis, Phileurus valgus, Hopliatrivialis, Canthon 

 cyanellus, Macrodactylus angustatus, CEmerigida, Heterachthes ebenus, Curius dentalus, 

 Llopus crassulus, Sinoxylon texanum, Acanthocinus, nodosus, Tetrops canescens, Hypor. 

 Jiagus punctulatus, Zabrotes obliterates and subnitens, Bruchus obsoletus and Apion segnipes. 

 Among northern forms which are to he found in the horeal zone are: Phellopsis 

 obcordata, Enchodes sericea, Boros unicolor, Laricobius erichsoni and Phyxelis rigidus. 



2 From notes made by Mr. Clifton, of this office, in his private diary, and which he 

 has kindly placed at my disposal, I am able to state that heavy snows ensued for the 

 three days following the 4th of February ; on the 9th the thermometer sunk to several 

 degrees below zero, continuing below for the next two days; heavy snow fell on the 

 11th, and the blizzard came on the 12th and 13th, traffic being suspended on the latter 

 day and the day following; on the 16th there was heavy rain and freezing. On the 

 7th of March a smaller blizzard visited the neighborhood, following a warmer spell. 



r> Very much the same conditions have been present over a wide extent of the 

 country east of the Mississippi Valley, as evidenced by correspondence from both 

 west and south. Certain of the correspondence from southern observers will be 

 quoted. Letters were also received from different portions of Indiana, Illinois, and 

 Michigan in regard to the winter weather couditions and its effects upon insects. 



4 It was not alone, perhaps, the severity of the winter of 1898-99 that brought 

 about these conditions as regards the scarcity or abundance of all the insects under 

 observation, since the previous winter was also colder than normal, and without 

 doubt had its effect on some of these species, although evidently not upon .others. 

 The effects of the last cold spell were felt upon plants as well as insects, peach trees 

 particularly suffering, as well as certain exotic ornamental trees which were intro- 

 duced here several years previously. 



