REVISION MALACOSOMA HUBNER IN NORTH AMERICA 25 



side (fig. 111). If they are laid around a very small twig, diey may 

 encircle the twig (fig. 109), or if they are laid around a somewhat 

 larger twig, they may only partially encircle it (fig. 110). If the spuma- 

 line is removed, however, it is always easy to determine whether the 

 eggs were laid as a basically flat clasping mass, since there will be a 

 definite edge where the last eggs were laid that will not be aligned 

 with the first eggs that were laid (fig. 109). 



The eastern tent caterpillar, M. americanum, often has been reported 

 as laying an cq,g mass which encircles the twig, when, in fact, the eggs 

 usually only partially encircle it (the spumaline may encircle it) and 

 may even be laid as a flat mass near the base of young trees an inch 

 or so in diameter (fig. 111). This is commonly the case in Minnesota, 

 western Wisconsin, and northern Michigan, but some or even most 

 egg masses are still laid on twigs in some areas. Egg masses collected 

 in eastern Wisconsin near Green Bay, in Indiana, Ohio, Virginia, 

 Kentucky, Kansas, Oklahoma, Missouri, Louisiana, and Texas were 

 all laid on small twigs or branches at varying heights above the ground, 

 even if the host was a small tree with a trunk diameter of less than 1 

 inch. The true situation throughout the rest of eastern North America 

 is not known, but all reports indicate that egg masses are laid on small 

 twigs, and no reports of &gg masses being laid at the base of small 

 trees have been found. This is a point which should be checked, 

 nevertheless, since it is unlikely that anybody has looked anyplace 

 except on twigs. No reason is known for the laying of some egg masses 

 near the base of small trees in Minnesota, Wisconsin, and Michigan, 

 but it has been suggested that eggs laid near the ground would be 

 covered by snow and thus protected from the rather cold midconti- 

 nental winter temperatures. 



Tents 



Not all species of tent caterpillars build tents, and of those species 

 that do build tents not all build them the same way or make the same 

 use of them. Those which build large, conspicuous tents {M. americanum, 

 M. incurvum, and M. californicum) usually start constructing the tent 

 soon after hatching, and they may build it right over the hatched egg 

 mass if it happens to be located near a suitable fork or branch. At 

 other times they may construct the first tent several feet away from 

 the egg mass. Larvae from each egg mass usually start building their 

 own tent, but sometimes larvae from several egg masses may fonn a 

 single large tent, especially when populations are dense. Quite often 

 the initial tent will be abandoned, and a second, third, or even more 

 tents constructed. The shape of the tent varies from relatively compact 



