156 TWENTY-FOURTH REPORT ON THE STATE MUSEUM. 



green interrupted stripe. The horns are slightly tapering, clubbed 

 at their tips, and two-tenths of an inch long. The legs and prolegs 

 are black. 



Fourth molt. Extending from August 14th to 16th. Imme- 

 diately following the molting, the head, collar, horns, anal shield, 

 anal plates and legs are flavescent ; in a few hours they become 

 shining black. The horns are but slightly enlarged at the tip, being- 

 less so than previous to this molt. The body is covered with numer- 

 ous, minute, shining, elevated points of the color of the ground upon 

 which they are placed. 



The mature larva is so fully and accurately described by Dr. Fitch* 

 as not to need redescription here. 



Subsequent collections of larvae were made and inadvertently 

 added to the above, preventing the observation pf the date of pupa- 

 tion of the brood. The pupation of the last occurred about the 15th 

 of September. Larvae were still observed in the field on the 30th of 

 September. 



Dr. Eights, of Albany, has informed me that a number of years 

 ago he observed on the line of the New York Central railroad, 

 between Albany and Schenectady, a species of caterpillar so exceed- 

 ingly abundant on and about the railroad track that the numbers 

 crushed on the rails by the passage of the trains caused the slipping 

 of the wheels of the engines to the extent of proving a serious incon- 

 venience in ascending grades. A notice of the interesting incident 

 was communicated by him to one of the journals of the day, in which 

 some account of the caterpillar was given. Although from the long 

 time which has elapsed since the event he is not able to indicate 

 positively the species, he believes it to have been A. senatoria, and 

 the locality of its occurrence in the vicinity of Center. 



This larva is found annually at Center in great abundance. In 

 the more favorable years for its multiplication" it abounds so exces- 

 sively that the smaller oaks, although very numerous there, are almost 

 as effectually defoliated as if a fire had swept over them. I have no 

 information of its occurrence in equal numbers at any other locality. 



The congeners of this species, pellucida, stigma, and rubieunda, 

 are rarely taken in the neighborhood of Albany. Of the latter 

 species the larva has not been observed, but a wing of the imago has 

 been found, by Mr. Meske, at Center. 



* Third, Fourth, and Fifth Reports on the Insects of 2V. F., 1859, section 322. 



