INSECT PESTS OF OHIO SHADE AND FOREST TREES 263 



ing willows are attacked most severely but not infrequently both 

 large and small appear as if swept by fire even as early in the season 

 as June 8. 



Food plants. The chief food plants of the spotted willow leaf 

 beetle in Ohio are the various species of native willow. In addition 

 to these, the writer has observed it on cottonwood and alder. 

 Doctor Carman (26) states that willow nursery stock in Kentucky 

 is sometimes seriously injured. 



Distribution. This insect occurs in all parts of Ohio. In other 

 parts of the country, it is reported to occur from Massachusetts 

 southward and as far west as Nebraska. In the latter state it has 

 long been listed as one of the enemies of cultivated poplars. 



Natural enemies. The natural controls of this species have not 

 been carefully studied. Harned (31) reports having seen lady 

 beetles on the leaves with the eggs and young larvae. It is likely, 

 particularly since these insects are known definitely to prey upon 

 the preceding species, that they attack this one as well. 



Control. When artificial control measures become necessary, 

 undoubtedly the most practicable is spraying with arsenicals. The 

 poison should be used in early spring at normal strengths; and, 

 since willow leaves are glossy and repel liquids, soap as a spreader 

 and sticker should be added to the spraying liquid. 



THE HICKORY HORNED-DEVIL OR REGAL WALNUT CATERPILLAR 



(Citheronia regalis Fabr.) 



While Citheronia regalis has not been recorded as being suffi- 

 ciently plentiful to do damage in Ohio it is the cause of frequent 

 inquiry because of the formidable appearance of the larva, and for 

 this reason is considered here. 



Description, The larva is the largest caterpillar occurring in 

 Ohio, when full-grown measuring as much as 5 inches in length and 

 almost three-fourths of an inch in thickness. The head is yellow 

 and the body a dark yellowish-green, the four pairs of abdominal 

 legs being almost black. The body is armed with spined horns, 

 most of the segments having on them four or more short black 

 horns arranged in a row around the body, but on both second 

 and third thoracic segments of the body are four large horns yellow 

 at the base and black at the tip. They are curved backward like a 

 goat's horns, and because of this resemblance the caterpillar is 

 sometimes known as the billy-goat caterpillar. A good idea of the 

 general appearance of the insect in this stage may be had from 

 Plate XLI, Fig. 1. It will be observed that the insect presents a 

 strikingly formidable aspect, and, this together with the fact that 



