Vol. xxvi] 



ENTOMOLOGICAL NEWS 



The damsel flies used were Enallagma and Ischnura, indi- 

 viduals of equal size being selected. Six were placed in each 

 cage with some enemy, such as Anax or a Dytiscid larva. The 

 six enemies in the several cages were of nearly equal size. 

 At the end of 36 hours the weeds Were examined in a white 

 porcelain tray. The results of the series are given in the fol- 

 lowing table. 



THE EFFICIENCY OF SHELTER 



The same method of placing the shelter was followed 

 throughout the series. In the second set of experiments 

 Myriophyllwn was used because its needle-like leaves offered 

 a different kind of shelter from that of Hlodea. The arrange- 

 ment was as follows: 



Cage 2, containing 3 bars with 3 plants each, displaced 80 

 cc. water. 



Cage 3, containing 4 bars with 4 plants each, displaced 170 

 cc. water. 



Cage 4, containing 7 bars with 7 plants each, displaced 375 

 cc. water. 



Cage 5, packed, displaced 845 cc. water. 



For the third set of experiments, Potamogeton crispits, a 

 fairly large plant, with long, broad leaves, was chosen. 



