THE CRANBERRY SPANWORM. 23 



opposite extremity. The color varies to a considerable extent from 

 mottled pale yellowish to brown, often with an olivaceous or greenish 

 tint. Those which have been recently captured in the District of 

 Columbia are reddish brown, mottled, streaked, and lined w'ith lighter 

 yellowish, red, and black. The head is strongly marked with trans- 

 verse irregular black bands. The thoracic segments are marked 

 above by a pair of thin median longitudinal lines. The second 

 abdominal segment l^ears on the dorsal surface a pair of prominent, 

 widely se})arated, mostly l)lack tubercles, but in some individuals 

 these are wanting. The penultimate segment also bears above a 

 smaller pair of black tubercles. The larva when full grown measures 

 an inch to upward of an inch and a fourth in length (SS-S?*""™) and 

 the greatest diameter is about one-eighth of an inch (S'""'). The singu- 

 lar construction of the legs, or rath(^r the lack of the intermediate legs 

 usually present in caterpillars of otlier families, is the cause of the 

 peculiar motions of the spanworms in crawling about in search of 

 food, Avhich have given them their popular names, "When in motion 

 a larva extends its body to full length, then brings the posterior legs 

 close to the anterior ones, causing the body to loop in the center. 

 The body is then stretched out again, these actions being repeated 

 alternately. 



When this spanworm is in repose it attaches itself to the foliage — 

 for example, to tlie stem of asparagus — by means of its anal pair of 

 legs and stretches out its body rigidly and at an angle so that its 

 natural colors harmonize with the foliage or with the landscape. 

 On this head Doctor Smith has remarked (hat on a section of cran- 

 berry bog on which this species is feeding the observer may stand in 

 the midst of thousands of them and see none until something starts 

 them into motion. Then it appears almost as though tlie entire bog 

 were alive. As the spawnworms hang somewhat tenaciously to their 

 food plants, they are undoubtedly present frequently in numbers 

 without anyone being the wiser. 



The half-grown larva is described by Doctor Forbes.^^ 

 The pupa, shown, ventral view, in figure (5 at cU is of robust form, 

 light greenish brown in color, and a little less than half an inch in 

 length (12'"''^) and about a third of that (4""") in width. 



DISTRIBUTION. 



The wide distribution nf this insect is shown \)\ the following list 

 of localities, based upon Doctor Packard's list, where the authorities 

 for each locality are given: ^Nfaine: Amherst, Cape Cod, Cotuit, 

 Xatick, Mass.; West Farms, Center, Albany, and Brewster, X. Y. ; 

 Philadelphia, Pa.; Lansing, Mich.; Dayton. Ohio (Pilate): Glen- 

 coe, Xebr. ; Cadet, Mo.: Centralia and elsewhere in Illinois; Wash- 

 ington and Brookhmd, D. C. ; Georgia; Calhoun, Dawson, and De- 

 55908°— Bull. fi«>— in 3 



