' The female has only rudimentary wings and is hairy, stout, and light 

 grayish in color. She is unable to fly and mating therefore takes place 

 wherever the female emerges from the pupa. 



The eggs are deposited in conspicuous masses of about 400 on the cocoon 

 where the female emerges. These are nearly spherical in shape, and yel- 

 lowish in color. The whole mass is covered with a frothy substance. 



APPEARANCE DUEING THE SEASON 



This insect spends the winter in the egg stage. The white egg masses 

 are often conspicuous objects on tree trunks and even on the sides of build- 

 ings in localities where the larvae have been exceptionally common. Young 

 caterpillars hatch in Iowa in June. In 1908 these were observed by the 

 writer at Shenandoah, June 6, for the first time that year. By June 15 

 larvae were common at the same place. 



After feeding about a month, 

 the caterpillar forms its brown- 

 ish, silken cocoon on the bark of 

 trees, on twigs or elsewhere. It 

 then transforms, first to the in- 

 termediate pupa stage, and then 

 to the moth. Consequently, in 

 Iowa another lot of eggs are de- 

 posited in midsummer and later, 

 in August and September, a new 

 lot of caterpillars appear. These 

 feed and mature late in Septem- 

 ber, the insect passing the win- 

 ter in the egg stage. 

 Egg mass of White-marked Tussock-Moth 



FOOD PLANTS 



The white-marked tussock-moth is best known as a shade tree insect and 

 is most destructive to such trees as elm, soft maple and linden. The larvae 

 feed on many other plants, among which are the poplar, willow, oak, ash, 

 catalpa, boxelder, birch, horse chestnut, and other trees. The insect is fre- 

 quently found on apple foliage and the writer once observed a caterpillar 

 feeding on a blade of corn. 



CONTEOL MEASURES 



Control measures may be directed in two ways; against the eggs and 

 against the caterpillars. 



The destruction of egg masses during the colder months is a most import- 

 ant measure. These masses are conspicuous and may be easily collected by 

 hand. In fact, school children in some localities have been encouraged to 

 gather these and are paid for so doing. Those egg masses which are out 

 of each can be treated with creosote applied by means of a sponge soaked in 

 this material and attached to a pole. 



In spring, trees not infested with this insect may be protected by placing 



