260 OHIO EXPERIMENT STATION: BULLETIN 332 



is about one-third of an inch long. The body is dirty yellowish, the 

 head brown and legs black. In general appearance the larvae re- 

 semble those of lady beetles. 



The pupae are attached by the tip of the body to the under- 

 surface of leaves, to twigs or to any nearby object. The free part 

 of the body is black and the rear dark brown, the legs, wings, etc., 

 being plainly discernible. 



Life history and habits. — The winter is passed in the adult 

 stage in the shelter of grass clumps, beneath stones, logs, bark or 

 any convenient protected situation. From their winter homes the 

 beetles emerge in late April or May, according to Lowe (29), making 

 their appearance in the vicinity of Syracuse, N. Y., from May 1 to 

 10. Soon the eggs are laid in the manner previously described, 

 hatching in from 10 days to 2 weeks. Usually about 2 weeks is 

 required to complete larval growth. 



Drops of white, ill-smelling milky fluid are emitted from 

 tubercles along the sides of the thorax when the insects are dis- 

 turbed. This evidently serves as a protection against predators. 

 In addition to the power to eject this milky liquid, the insects can 

 also retract it, which they do when the disturbance ceases. Thus 

 if they are alternately disturbed and let alone they will likewise 

 alternately expel and withdraw the drops. At the tip of the larval 

 body is a sticky disc, which not only aids the insect in crawling dur- 

 ing the active feeding period but also serves to suspend the body 

 when larval growth is complete and pupation is about to occur. The 

 pupal stage lasts about 2 weeks. It is Doctor Lowe's belief that 

 two and possibly three broods occur in New York State. Early in 

 August the insects seek their winter quarters. 



Nature of work. — Both adults and larvae of the cottonwood 

 leaf beetle feed upon the foliage of the host, and in addition the 

 growing tips of basket willow are so seriously mutilated as to cause 

 their death. The dying of the shoots causes branching and bushi- 

 ness, thus ruining the willows for basket purposes. As a destroyer 

 of the foliage of shade and ornamental trees, this pest is sometimes 

 serious, particularly in the western states where the cottonwood is 

 prized for this purpose. 



Food plants. — Various species of Populus are attacked by this 



species, the cottonwood probably being preferred above all others. 

 Many willows also are attacked and of this group of hosts, the 

 Osier or basket willow of Europe, Salix viminalis, seems the chosen 

 sort when available. ' 



