34 ENTOMOLOGICAL NEWS. [Feb., '03 



teneral imaginal Odonata (as well as more or less crumpled de- 

 tached Odonate wings) were entangled in the remains of spiders' 

 webs. The open doors of the boathouse were on the north 

 side, the opposite south wall was not so easily accessible from 

 the water as were the east and west walls on which the exuviae 

 were chiefly found. On these two walls they reached to a 

 height of twelve feet above the water. Bach of these two 

 walls had a single window in the middle, that of the west wall 

 being closed, that of the east wall freely admitting light. We 

 were not able to find any correlation in the distribution of the 

 exuviae with the relative amount and distribution of light. 



We collected most of the unbroken Odonate exuviae seen in 

 this boathouse and I have identified them as follows : Agrioninse 

 I sp. I S 4 9 , Gomphus sp. {sordidus group) 4^19, Dromogom- 

 phus spinosus 2^2$, Didymops trajisversa 4^1$, Neu7'ocordulia 

 obsoleta 15 S 16 9 , Tetragoneuria cynosiira 8 S 10 9 , Epicordidia 

 princeps i 'S 4 9 , in all 73. The almost entire teneral Odonata 

 found in the remains of webs were Dromogomphus spinostis i 9 , 

 Neurocordula obsoleta i 9 , and Epicordulia princeps i 9 ; the ab- 

 domen of D. spinosus and the thorax of E. pri?iceps had been 

 partly eaten by something. The spiders' exuviae have been 

 kindly determined by Dr. T. H. Montgomery, Jr., as of Dolo- 

 medes iirinator or D. idonens. As the above-named Odonata 

 are usually seen flying not later than July in this region, it is 

 quite likely that the transformations had occurred long previous 

 to our visit to the boathouse. 



The general condition of affairs strongly suggested that the 

 spiders had preyed upon the newly transformed dragonflies,* a 

 possible explanation of the generally observed rarity of such a 

 species as Neurocordulia obsoleta in the imago state as contrasted 

 with the abundance of its exuviae found here. 



Prof. Needham has called attentionf to a similar contrast in 

 the genus Ophiogomphus , for which a similar explanation is 

 perhaps to be sought. 



* Years ago I observed young Dolotnedes sexpunrtatus feeding upon 

 the soft parts of recently transformed imagos of Ischnura verticalis and 

 /. {Nehalennia) posita which were not yet able to fly. Trans. Amer. Ent. 

 Soc, XX, p. 205, 1893. See also McCook, Amer. Spiders and their Spin- 

 ning Work, iii, p. 23, 1893. 



t Can. Ent., xxix, p. 183 ; xxxi, p. 233. 



