on isolated trees is to prune off and burn twigs containing egg 
masses. The destruction of tents on cold, cloudy days when the 
tents are still small is also effective. 
The prairie tent caterpillar, Malacosoma californicum lutescens 
(Neumoegen & Dyar) occurs throughout the Great Plains area 
east of the Rocky Mountains to central Texas. Its hosts are re- 
corded as choke cherry, Rosa, willow, wild plum, and Ribes. Male 
adults range from dark reddish-brown to very light yellow; fe- 
males are yellowish to medium reddish-orange brown. The fore- 
wings are crossed by light yellowish lines, and the wingspread is 
about 87 to 50 mm. Full-grown larvae are about 50 mm. long. 
The head is blue, mottled with black, and sparsely covered with 
fine whitish to orange setae. The mid-dorsal area of each ab- 
dominal segment is marked with an elongate, somewhat pointed, 
blue-white dash. These dashes combine to form a broken mid- 
dorsal stripe. 
Eggs are laid in flattish, clasping masses on twigs and branches 
and are covered with light brown or grayish spumaline. The 
larvae construct relatively large tents that look like those of the 
eastern tent caterpillar. Defoliation is usually confined to 
branches, but during outbreaks trees may be completely defoli- 
ated. Because of the low value of its hosts, the species is of 
minor economic importance. 
Malacosoma tigris (Dyar), the Sonoran tent caterpillar, occurs 
in the Southern Great Plains, Southern Rocky Mountains, the 
Southwest, and Mexico. So far, it is not known to occur farther 
eastward than central Texas. Its host plants are various oaks 
and possibly other species. Eggs are laid in encircling bands on 
very small twigs, occasionally dead twigs. The masses differ from 
those of other members of the genus in not being covered with 
spumaline. The larvae construct relatively small tents on which 
they congregate to molt. They are usually formed near the end of 
each larval instar. This species does not appear to be of much 
economic importance, unless it occurs in association with other 
defoliating species. During recent years, it has combined with 
the forest tent caterpillar in heavily defoliating oaks in south 
central Texas. : 
The western tent caterpillar, Malacosoma californicum pluviale 
(Dyar), occurs primarily in western America. However, spotted 
infestations also occur eastward across central Canada to Quebec. 
It has also been collected in New Hampshire, New York, and 
northwestern Minnesota (687). Alder, shadbush, willow, choke 
cherry, birch, apple, plum, cherry, and trembling aspen are known 
to be attacked. Full-grown larvae are predominantly black and yel- 
low or yellow-orange. The head is mottled blue-black and sparsely 
covered with fine yellow-orange setae. The dorsum of the abdomen 
is marked by a stripe formed by a series of elongate blue, white, 
somewhat pointed dashes, one per segment. 
Eggs are laid in flat, clasping masses covered with brown or 
dark brown spumaline. The tents are similar to those of the 
eastern tent caterpillar. The species is of little or no economic 
importance in eastern America. 
The forest tent caterpillar, Malacosoma disstria Hubner, occurs 
throughout most of the United States and Canada and feeds on 
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