114 UNITED STATES NATIONAL MUSEUM BULLETIN 2 76 



EGG MASS. — The eggs are laid as a basically clasping mass on 

 small twigs (fig. 109), branches (fig. 110), or even the trunks of small 

 trees (fig. 111). Egg masses laid on small twigs may appear to encircle 

 the twig, but careful examination will reveal an irregular "seam" 

 where the last row of eggs meets the first. Sometimes the last row may 

 even be laid on top of the first row if a large female has laid her eggs on 

 a small twig. All reports in the literature indicate that the eggs are 

 normally laid on small twigs. In Minnesota, western Wisconsin, and 

 northern Michigan, however, egg masses are often laid about 6 inches 

 above the ground on the trunk of small trees from ^ to 1 }^ inches in 

 diamxter (fig. 111). At the same localities some egg masses may also 

 be laid in the usual fashion on small twigs or branches. 



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. 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 

 midcontinental winter temperatures. 



The spumaline covering the eggs of americanum is very dark brown, 

 which in most cases distinguishes them from those species laying 

 similarly shaped egg masses {M. calif ornicum and AI. incurvum), but 

 whose spumaline is usually lighter colored. 



TENTS.— See page 25. 



COCOONS. — Cocoons are fairly tightly constructed, usually lack a 

 conspicuous outer envelope of silk such as M. disstria spins, and are 

 suflfused with a bright yellow powder. 



FOOD PLANTS. — Preferred hosts for oviposition are members of 

 the genera Primus, Malus, Crataegus, and other related plants. Food 

 preferences are not as restricted as oviposition preferences, and larvae 

 will eat many deciduous trees and shrubs, especially in the last instar. 

 This, no doubt, accounts for the extremely large number of host 

 plants which have been reported in the literature. 



A good example of the diff'erence in oviposition and feeding prefer- 

 ences was found near Kerrville, Texas (Coll. No. 412). Several large 

 tents were found in an isolated clump of young oak (Quercus shumardii?) 

 about 15 feet tall. Oak is not commonly regarded as a host oi americanum, 

 so a careful search was made for egg masses. None were found on the 

 oak, but eight egg masses were found on a small, completely defoliated 

 wild plum growing beneath the oaks. This plum tree was less than 2 

 feet tall and could not possibly have supported the caterpillars which 



