INSECTS AFFECTING PARK AND WOODLAND TREES 523 



black ; witltli 3.5 mm. Tlic body is as in the previous stajje, but the warts 

 on the cervical shield are not distinctly darker. The dorsal blackish or ])ale 

 gray shade is in triplicate on joints three and four. Spiracles white in a 

 fine black border. The body is often bright yellow, as are the dorsal tufts, 

 and even the hair is yellowish. 



Oak tussock caterpillar 



Halisidota viaciilata Ilarr. 



A black-headed caterpillar about i^ indies long, tliickly clotiied with yellowish 

 hairs and black tufts of the same, feeds in Se[)tetnl)er on a variety of trees. 



The larva of this species has a decided preference for oak, thouo^h it 

 has also been recorded as feeding on poplar, willow and alder. It may be 

 recognized by its black head in conjunction with the thick covering of tufts 

 of bright yellow and black hairs. The two posterior thoracic segments and 

 the first abdominal segment are covered with mi.xed yellow and black hairs, 

 those of the former overhanging the head. Tiie first to eighth abdominal 

 segments inclusi\-e, licar a dorsal black tuft, the largest being on the sev- 

 enth and eighth. There is also a black tuft on each side near the base of 

 the first and eighth abdominal segments. The hairs of the second to sev- 

 enth segments are bright yellow, while those on the ninth and tenth are 

 mi.xed with l)lack. The parent insect has pale yellowish wings mottled 

 with dark I)rown. the hind wings being pale straw yellow. 



Pale tussock caterpillar 



Halisidota tcsscllaris Hiibn. 



A yellowish, brown-headed caterpillar about i '4 inches long, clothed with delicate 

 buff yellow hairs and with four light brown dorsal jiencils of the same, feeds in the fall on 

 a large variety of trees. 



The larva of this species is a very genera> feeder, it having been 

 recorded on about 30 trees and shrubs, representing 10 natural orders. It 

 can hardly be considered a dangerous species, though exceptional condi- 

 tions might enable it to multiply to an unprecedented extent. The larva 

 has been described by Riley as. follows : 



The hairs delicate 1)uff yellow ; four dorsal pencils in front, of light 



