490 



Phylum Arthropoda 



made by cutting cheesecloth in 2.5 in. squares, fitting cotton into end 

 of vials, removing, covering with cheesecloth, and replacing. The plugs 

 should be tight and closely fitting on all sides without wrinkling of 

 cheesecloth. Vials are best cleaned by soaking in hot water without 

 soap and then rinsing. 



Egg boxes with square compartments in two rows of six each. Four 

 vials stand upright in each compartment; thus 48 cultures occupy the 

 space taken by a dozen eggs. Egg boxes are placed side by side on 

 shelves of the incubator so that the ends are visible and may be marked 

 according to convenience. 



Tweezers for handling wasps and caterpillars. 



Gelatine capsules for isolating pupae for virgin females. 



Petri dishes (inside measurements, 9 cm. wide, 1 cm. deep) with 

 circular paper cut to fit inside. 



Incubator regulated to 30 C. (This is for the maximum speed 

 consistent with safety and normal development. Wasps will stand 

 three or four degrees higher temperature, but do not develop as well. 

 At lower temperatures development is normal but retarded. Body 

 coloration is black at lower temperatures, yellow at higher.) The 

 incubator may be made of %" board. Shelves should be frames covered 

 with wire netting (%" mesh), and 17" deep to allow space in front of 

 1 2 -inch egg boxes for petri dishes. There should be about a 4-inch 

 clearance space between the shelves for 70 mm. vials plus the protruding 

 ends of cotton plugs. There should be 6.5 inches above the upper shelf 

 for a thermostat which is screwed to the top and regulated through a 

 small hole made in the top. The heating unit is placed beneath the 

 lowest shelf. Be sure to place a pan or piece of asbestos directly over 

 the heating unit to distribute the heat. Test various regions with a 

 thermometer. The incubator may be 36 inches wide and as high as 

 convenient. If much space is not needed a chicken incubator may be 

 used, heated from above by several small carbon bulbs which should be 

 arranged at least in part in parallel. If they are all in series, burning 

 out of one will cause the temperature to drop. Regulate the incubator 

 for temperature at the level of the cultures. 



Technique. Adult wasps may be kept for several months in the re- 

 frigerator but will not live unless they have been reared at low tempera- 

 tures, 20 to 25 C. This is the best way to keep stock. Place adult 

 females in shell vials. Feed with honey water by dipping a wire into 

 honey, then into water, and then touching to the inside of the vial, thus 

 leaving a drop. In new vials the drop is likely to spread, but after they 

 are once used and washed in warm water without soap, an invisible 

 coating of grease causes the drop to stay in one place. Set vials of 

 stock wasps in a tight tin box in which has been placed one or more 



