July 15, 1915 



Asparagus-Beetle Egg Parasite 



307 



another vial and supplied daily with fresh food. At maturity they went 

 into the soil in the bottom of the vial, and in due time either adult bee- 

 tles or the parasites issued from the soil. 



METHODS USED FOR REARING THE PARASITES IN CONFINEMENT 



The adults of the parasite T. asparagi were captured in the field and 

 confined in the laboratory in vials, measuring 100 mm. in length and 

 28 mm. in diameter. The ends of the vials were covered with cheese- 

 cloth, as better results were obtained when this was used than when the 

 vials were stopped with cotton plugs. Each day a supply of fresh 

 asparagus-beetle eggs was collected in the field, brought into the labora- 

 tory, and a certain number placed in a vial with each parasite. The eggs 

 remained with the parasites for 24 hours, when they were removed, the 

 number parasitized and the number eaten by each parasite being recorded 

 and the twigs bearing the eggs placed in moist sand, so that the eggs 

 might hatch. 



As soon as the young beetle larvae hatched, they were confined in \'ials 

 about one-third full of moist earth, and supplied with fresh food each 

 day. As soon as the beetle larvae were full grown, they were allowed to 

 go into the soil in the vial and pupate. In several cases the pupal cells 

 were formed near the glass, and it was possible to observe the naked 

 parasitic larvae in the cell after they had completely consumed their host. 



LENGTH OF LIFE OF ADULTS IN CONFINEMENT 



Tables I, II, and III show the length of life of adults collected in the 

 field and those reared in the laboratory, and the number of eggs para- 

 sitized and eaten by each parasite. 



Tabi<e I. — Length of life of the parasite Tetrastichus asparagi, reared at the Riverhead, 



N. Y., laboratory in igi2 



a The average length of life was 7.83 days: the maximum, 25 days. 



* All died on Sept. 9, when they were left fromi morning until afternoon without any eggs in the 

 vial. 

 " This parasite was accidentally killed. 

 <* During the last 3 days no asparagus-beetle eggs could be obtained. 



