INSECT PESTS OF OHIO SHADE AND FOREST TREES 259 



P. strobus. It probably feeds on other species of pine, but in most 

 of the published records concerning it, white pine is mentioned 

 particularly ; hence this tree must be the usual and preferred host. 



Distribution. — This insect is most prevalent in the eastern and 

 east-central states, but has been reported as far west as Iowa. 

 Under Ohio conditions it is more prone to attack isolated trees than 

 those growing in thick, pure stands, and is a pest of rural rather 

 than city trees. It has been reported and observed in various sec- 

 tions of the State, one of the most destructive outbreaks appear- 

 ing in the white pine plantings of the Oberlin Waterworks Farm, 

 and reported by A. E. Taylor, of the Department of Forestry 

 of the Ohio Station, October 8, 1915. In this instance it was esti- 

 mated that 50 percent of the trees were attacked, and of this num- 

 ber 5 percent were defoliated. 



Natural enemies. — The writer has bred from the cocoons a 

 Hymenopteron determined by S. A. Rohwer, of the U. S. National 

 Museum, as Lagrotis diprioni Rohwer. Cook (27) has reported a 

 ■chalcid parasite, Perilampus hyalinus Say, and Felt (28) reports 

 Limneria lophyri Riley. 



Control. — Since the larvae feed gregariously, hand picking fre- 

 quently is practicable but where the infestations are extended, 

 spraying with the arsenate of lead poison is advisable. 



THE COTTONWOOD LEAF BEETLE 



{Lina scripta Fabr.) 



The writer has observed the cottonwood leaf beetle but a few 

 times in Ohio; but, because of its destructiveness in other states 

 particularly to basket-willow plantations, it is treated here in a 

 fairly comprehensive manner. 



Description. — The adult is a hard-shelled beetle, elongate and 

 rounded in form, and averaging a little less than three-eighths of 

 an inch in length. Beneath, it is dark metallic green. Above, the 

 head and thorax are black, the latter being bordered with dark 

 yellow or red. The wing-covers are gold, marked with three inter- 

 rupted lines. Great variations exist, however, in the color and 

 markings of the wing covers, as will be seen by a glance at the 

 accompanying Plate XL, Fig. 2, the range extending from almost 

 pure gold to almost unbroken black. 



The eggs are light yellow, are almost one-fifteenth of an inch 

 long and are deposited in a slightly slanting position, most fre- 

 quently on the underside of the leaf. 



The larva upon first hatching is about one-twenty-fifth of an 

 inch long and is black or very dark brown. Upon maturity the larva 



