REVISION MALACOSOMA HUBNER IN NORTH AMERICA 191 



males), having females with a distinctive, sclerotized genital plate, and 

 in feeding on many different hosts. The most important similarities 

 between the two other species, tigris and constrictum, are their restriction 

 to oaks, construction of small tents each time they molt which are used 

 only for attachment during molting, and having dark colored females 

 and light males. As far as differences are concerned, they occur in 

 different geographic areas, and differ in genitalic characters, but the 

 biggest difference is in the egg masses, wlaich are covered with bubbles 

 of yellowish spumaline by constrictum, but which are essentially not 

 covered with spumaline by tigris. 



The second North American group is made up oi americanum, incurvum, 

 and calif ornicum. All three lay clasping egg masses, construct large 

 tents, usually have the forewings crossed by light lines (but sometimes 

 the reverse is true in some individuals and populations of californicum 

 and VKurvum), and have females with relatively large ovipositors. 

 Within this group californicum and incurvum are very closely related, and 

 americanum stands alone, differing in the ways pointed out in the 

 diagnoses (pages 112, 113). 



