42 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



The relative abundance of many species varies greatly from year 

 to year, while the numbers of others are relatively constant. Thus 

 in 1925 Junonia lavinia was abundant, and the handsome " wet " form 

 was very common in the restricted localities where it is found. In 

 the three following years it was much less common, and the " wet " 

 form did not occur. But in 1929 it was very abundant, and the 

 " Avet " form reappeared, though in small numbers. 



Pyranieis cardui was very common in 1926, frequent in 1927, but 

 absent in 1928, 1929, and 1930. P. atalanta Avas common in 1926, 

 when the '' wet " form occurred, and Avas also common in 1929, when 

 the " Avet " form was again found. 



Danmi^ plexippus suddenly appeared in great abundance following 

 a heavy rain in the middle of September, 1930. Before the rain it 

 had been unusually scarce. 



Pieris frotodice was rather frequent in 1926, but was not seen again 

 until late in the summer of 1930. 



Strymon m-alhum Avas found in 1926, Avas rather common in 1927, 

 but was not found in 1928, 1929, or 1930. 



Basilarchia ofrthemis astyanaoa was unusually common in 1928, but 

 it Avas very scarce in 1929, and still scarcer in 1930. 



The year 1929 was a rather curious one. In the spring hibernated 

 individuals of Junonia lavinia^ usually rare, were very common, and 

 the butterfly rapidly increased in numbers, becoming extraordinarily 

 abundant. Thmiaos icelus was unusually common. The little copper 

 {Oh7ysophanus jjhlaeas) was so common that no less than 30 were 

 taken in a single afternoon in a field at Beltsville, Md., and it was 

 noticed in various places where it had never been seen before. Phyd- 

 odes tharos, always common, Avas exceedingly abundant. C olios eury- 

 theme for the first time Avas taken in the District in the spring, and 

 later became more common than C. philodice. A curious feature con- 

 nected with this butterfly Avas that in this year the light forms greatly 

 predominated OA-er the deeply colored form, most of the individuals 

 seen upon the wing appearing singularly pale. Late in the summer 

 Phoebis euhule became unusually numerous, and for the first time a 

 female was found within our limits. 



The spring of 1930 was unusually cool and dry. P amies zabulon, 

 Argynnis cyhele^ and Euphydnjas phcueton appeared at least a week 

 earlier than the normal date. Strange to say, Argynnis idcdia was 

 not affected, appearing first on June 15 as usual, while Neonynipha 

 eurytus was first seen, as in former years, on May 30. Argynnis 

 cyhele, Poanes zdbulon^ Polites coras, and Neonympha eurytus were 

 unusually common, but all the other local butterflies were scarce, 

 especially the skippers. Even the silver-spotted skipper {Epargyreus 

 tityrus) and the sooty skippers {Thoryhes pylades and T. daunus). 



