REVISION MALACOSOMA HUBNER IN NORTH AMERICA 15 



difficulty from the road while driving from 20 to 50 m.p.h. This per- 

 mitted large areas to be covered relatively rapidly, and obviated the 

 necessity of stopping every few miles to look for caterpillars. The diffi- 

 culty in locating larvae which do not construct tents can be illustrated 

 by the fact that of the nearly 500 collections made in 1960 and 1961, 

 only 7 were made of M. disstria, which does not build a tent — 6 of the 

 7 were made incidental to collecting tentbuilders and the other 1 was 

 collected as a result of very conspicvious defoliation. 



Equipment 



The major piece of equipment was a mobile insectary-trailer (fig. 

 336) containing 45 built-in rearing cages, a workbench, and sufficient 

 storage space for all necessary collecting and preservation materials. 

 The exterior of the trailer was fitted with plywood flaps that protected 

 the cages when the trailer was being moved; they could be propped 

 open for shade in warm localities, or removed for direct sun in cool 

 areas. The roof was constructed vv^ith a dead-air space, vented, in- 

 sulated with fiberglass and covered with aluminum sheeting. This 

 combination, plus a white exterior and cross ventilation, kept the 

 temperature inside the trailer at or below the outside air temperature. 

 This was quite satisfactory for rearing Malacosoma, 



The cages (18 inches high, 18 inches wide, 24 inches deep) opened to 

 the inside aisle of the trailer. All sides were screened with 50 X 50 mesh 

 bronze screen to confine small larvae and prevent rusting. The floor of a 

 cage was made of plywood which also sei'ved as the ceiling of the cage 

 below. The cages were built-in; they should have been removable so 

 they could be cleaned more easily, or disinfected if necessary. 



Freshly cut foliage was provided as often as necessary, and was held in 

 1-quart mason jars filled with water. The space in the mouth of the jar 

 not filled by branches was plugged with a wad of paper towels to prevent 

 larvae from crawhng or falling into the water. To prevent the jars from 

 tipping over when the trailer was moved and also to conserve space, two 

 holes, the size of the inside diameter of the jar ring, were drilled in one 

 side of the floor of each cage, alternating sides with tiers of cages. Jar 

 rings were screwed to the ceiling and to the floor around the holes. 

 Mason jars were then screwed into the rings from below, permitting 

 the base of the branches from the cage above to project into the cage 

 below. This resulted in a saving of about 7 inches of vertical space per 

 cage, in addition to providing firm anchorage for the jars. The jar rings 

 on the floor of the cage were used to hold jar caps in place over the holes 

 if the cage was to be used for some other purpose. Of course, with this 



