Haliplidae 449 



Temperatures up to about 75 ° F. had no detrimental effects, winter or 

 summer, but much higher temperatures were destructive. Food was 

 furnished not oftener than once a month during the winter since the 

 beetles require little at this season, and the food will remain in good 

 condition for a long time. During the summer, these conditions are re- 

 versed. The beetles require more food because they are more active and 

 the food will soon deteriorate. As often as every other day a little 

 food was added. 



When eggs appeared, they were usually removed to separate finger 

 bowls which contained water. The temperature was maintained at 

 about 70 F. No particular attention was paid them until hatching 

 time. Very few eggs failed to hatch. 



The larvae were very easy to rear in the laboratory when a few es- 

 sential factors such as food, temperature, and condition of the water, 

 remained about constant. They were isolated in stender dishes which 

 contained water to a depth of about one inch. During the warm days of 

 summer when the temperature was much above 75 F., the water was 

 changed daily and all unconsumed food was removed. Either the water 

 was removed by means of a large pipette or the larvae were removed 

 to new culture dishes. In order that the condition of the culture dishes 

 might be observed easily, they were arranged on a shelf one row deep. 

 Covers were placed on the dishes to check evaporation. They were never 

 exposed to direct sunlight. 



The pupa is the most difficult stage to obtain because the larvae will 

 not pupate unless conditions are just right. Instead, they will remain 

 larvae or will die. Nevertheless, the pupae of all species studied were 

 secured. When the larvae had reached the 3rd instar they were trans- 

 ferred to a smaller stender dish containing a little water and food. A 

 branch of a water plant was so arranged that it extended over the top 

 of the dish in order that the larvae could crawl out to pupate. This small 

 dish was placed inside a larger stender dish which contained a small 

 amount of earth. This earth had been taken from the shore of the lake 

 in the vicinity of the place where the larvae would naturally pupate. 



Before they will enter this earth it must have the right moisture con- 

 tent. This seems to be the most important factor. If it is too wet or 

 too dry they will not construct the pupal chambers. It was found that 

 if the earth was just damp enough to hold together, the larvae would 

 pupate. A few drops of water were added from time to time to prevent 

 undue drying. Fungous growths must be watched for and eliminated. 

 They were largely avoided at the outset by moistening rather large 

 quantities of this shore material, allowing it to stand for a few days be- 

 fore using, and selecting those samples which showed no fungous growth. 



Spirogyra proved to be the only kind of food that gave satisfactory 



