INSECTS AFFECTING PARK AND WOODLAND TREES 



523 



black ; width 3.5 mm. The body is as in the previous stage, but the warts 

 on the cervical shield are not distinctly darker. The dorsal blackish or pale 

 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 macula t a Harr. 



A black-headed caterpillar about 1% inches long, thickly clothed with yellowish 

 hairs and black tufts of the same, feeds in September on a variety of trees. 



The larva of this species has a decided preference for oak, though 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 mixed yellow and black hairs, 

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

 segments inclusive, bear 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 

 mixed with black. The parent insect has pale yellowish wings mottled 

 with dark brown, the hind wings being pale straw yellow. 



Pale tussock caterpillar 



Halisidota tessellaris Hiibn. 



A yellowish, brown-headed caterpillar about 1% inches long, clothed with delicate 

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

 a large variety of trees. 



The larva of this species is a very general 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 buff yellow ; four dorsal pencils in front, of light 



