INSECT NOTES FOR I9IO. 3 



After a few days all the larvae had left the mines and were feed- 

 ing on the surface. Examination proved them to be the larvse 

 of B. canadcnsisclla. Thus it is seen that this species passes 

 the first 2 months of its existence as a leaf miner in the same 

 manner as the Apple Bucculatrix. 



The young larva is' rendered quite conspicuous by the promi- 

 nence of the black ganglia of the ventral nerve cord, visible 

 even when within the leaf mine. The full grown larva has 3 

 pairs of claws on each of the intermediate abdominal prolegs, 

 but in the earlier stage there is but one pair. The nerve ganglia 

 become less noticeable as the larva increases in size. 



Fortunately for the birches, the larvae do not reach their 

 greatest development until late in August, so^ that there can be 

 but little permanent injury done to the tree. In the region 

 about Orono, Betula populifolia and papyrifcra as well as the 

 cultivated B. alba show the greatest amount of injury, while 

 B. Icnta and httca are less severely treated. The alder (Alnus 

 incana) when near a birch tree may also be attacked, though 

 the injury to the leaf is not so great. 



DIPTERA. 



From among a number of observations upon the biology of 

 various species of Diptera and reserved for publication else- 

 where, the following have been selected as being of general 

 interest. As in former years, Rhagolctis pomondla (Apple 

 maggot) heads the list of the more injurious Diptera of Maine. 



Parthc7togencsis and Pcudogenesis in Tanytarsus. 



Notes on the psedogenetic reproduction of Tanytarsus dissi- 

 niilis have already been published in Science (Nov. 25, '10). 

 To the observations made there may be added that although 

 many adults were reared this year no males were among them. 

 One female, accidentally held captive by its wings in its own 

 pupal skin, was observed to lay eggs. These eggs were trans- 

 ferred into distilled water, but unfortunately immediately dis- 

 integrated. Later more eggs were obtained which had been 

 laid by newly emerging females. The eggs in each string, 

 about 60 in number, are arranged side by side, but lie somewhat 

 obliquely in a single row, surrounded by gelatine. Each egg is 



