10 



BULLETIN 902, U. S. DEPARTMENT OF AGRICULTURE. 



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The female died June 20, and the male July 31. 



The second female, which developed September 6, 1915, deposited 

 193 eggs beginning March 26 and ending July 26, 1916. She died 

 July 30. 



Females collected in the field and confined deposited from 27 to 

 163 eggs each, indicating that many of their eggs had been deposited 

 before they were confined. 



HABITS AND BEHAVIOR. 



It was noticed in the occurrence of this insect in Otero County, 

 Colo., that the beetles could best be collected during the middle of 

 the day, the time when they were most active and were out on the 

 plants in larger numbers. Earlier or later in the day 

 they were usually found lower down on the plants 

 around the crown or in cracks in the ground. 



In order to collect them in numbers, a collecting bottle 

 fixed somewhat as follows was used and found satis- 

 factory: The bottoms of two small vials are broken out 

 and then put end to end through the cork of the larger 

 bottle (fig. 4). Upon inserting the neck of the outer 

 vial over a beetle, it will invariably jump up into the 

 vial. The neck is useful in that the beetle has a sup- 

 port to fall on if it does not secure a footing on the 

 side of the vial. Hundreds of beetles can be collected 

 in a bottle of this kind with small possibilities of any 

 escaping. This form of bottle has been successfully 

 used for the capture of other species of flea-beetles. 



Adults mated from the middle of June to the middle 

 of July, and were sufficiently abundant to do noticeable 

 damage to small plants. Small radish plants were very 

 much injured by the beetles eating into the stalk at 

 the top or just below the surface of the ground, causing the plants 

 to wilt and die. 



In rearing experiments considerable care is required to see that 

 the soil, or whatever the insects are in, does not become too wet or 

 too dry. If the eggs are allowed to become too wet, they do not 

 hatch; if not moist enough, they shrivel and dry up. In general, eggs 

 require soil that is moderately moist. 



The greatest difficulty in life-history studies was encountered in 

 the larval stage. The larvae were easily killed by excessive mois- 

 ture, especially when accompanied by heat. Probably several 

 thousand larvae hatched but only a few lived to be adults. The 

 most susceptible period is just after the larvae have hatched. The 

 laboratory temperature varied from 65° to 80° F. or above, with the 

 maximum temperature for the larvae about 70° F. This approxi- 



ul 



Fig. 4.— Device 

 for collecting 

 flea -beetles 

 for study. 



