45° Phylum Arthropoda 



results for Peltodytes edentulus, P. sexmaculatus, P. lengi, and Haliplus 

 immaculicollis. Beetles of these species have been kept living on this 

 kind of food for 18 months. During this time, they have laid eggs that 

 hatched. Nitella was the only food that gave successful results for 

 Haliplus cribrarius and H. triopsis. They have been kept alive for 

 about 9 months. 



The larval food without a doubt is algae. The species of Peltodytes 

 and Haliplus immaculicollis feed exclusively on filamentous algae. H. 

 cribrarius and H. triopsis feed upon Chara and Nitella. 



The larvae are free from cannibalism, and any number may be kept 

 together. 



M. E. D. 



Reference 

 Family Dytiscidae 



For the feeding of Dytiscus see p. 242.* 



Family gyrinidae 



REARING GYRINIDAE** 



THE food of adult Gyrinidae consists of animal matter that has 

 fallen on the surface of the water. Captive Dineutes have been in- 

 duced to feed on dead flies and on bits of raw beef that were made to 

 float by spearing them on toothpicks. Never would they feed unless the 

 meat was at the surface. 



The eggs are laid on submerged vegetation or submerged portions of 

 emergent vegetation. In captivity in June and July eggs of both Di- 

 neutes (D. nigrior, D. hornii, and D. discolor) and Gyrinus were laid 

 on aquarium plants and on the sides of the container both above and 

 below the water line. Those laid in the air dessicated. When females 

 were brought from the field and placed in aquaria most of them laid eggs 

 within the first 12 or 18 hours. From 20 to 50 eggs were usually laid by 

 a single Dineutes. 



Young Dineutes larvae feed by sucking. They were fed on small 

 tubificid worms. The larvae will also attack and suck their fellows. 

 The larvae come to shore to build their pupal cases, whence they emerge 

 in a few days. 



M. E. D. 



♦Editor's Note: Several members of the family Dytiscidae have been kept alive for 

 some months in a balanced aquarium on a prepared fish food consisting of "a mixture of 

 cereal, powdered shrimp, and ground ant 'eggs.' ' : Particles of this food were seized and 

 devoured with apparent eagerness. M. E. D. 



♦♦Abstracted from an article in the Bull. Brooklyn Ent. Soc. 20:101, 1925, by Melville 

 H. Hatch, University oj Washington. 



