118 



BULLETIN 417, U. S. DEPARTMENT OF AGRICULTURE. 



BRIEF DESCRIPTION OF LARVA. 



First stage. — Small, rather stout. Average length of 10 specimens, 7.8 mm.; width, 

 2 mm. Caudal appendages 2.4 mm. long, straight, slender, bearing many long slender 

 spines. Color blackish bronze above, ventral plates dark brown. 



Second stage. — Stout. Average length of 10 specimens, 14.4 mm.; width, 3.3 mm. 

 Caudal appendages long, rather erect,"and curved upward beyond dorsal protuberance 

 which arises less than one-half the distance between base and tip. Color slightly 

 lighter than in first stage. 



Third stage. — Robust in form. Average length of 10 specimens, 22.5 mm.; width, 

 4.3 mm. Caudal appendages similar to those in second stage, dorsal protuberance 

 prominent, acute. Color bronze to blackish bronze, with pronounced metallic luster. 

 No reddish-brown patch on dorsum of last segment in second and third stages. 



LENGTH OF TIME REQUIRED TO COMPLETE THE LARVAL STAGES. 



Observations were made on larvae in 1911 to determine the length 

 of time required to complete each stage. The records indicate that 

 the first stage requires 4 days, the second 8, and the third 14; about 7 

 days additional are required in making cavities for pupation. 



Table 28. — Food eaten by larvae of Calosoma chinense. 







Number 



Number 











Estig- 



Hyphan- 











me.ne 



tria 



Number 





No. 



Date 



hatched. 



acraea 

 cater- 

 pillars 



cunea 

 cater- 

 pillars 



Porthet- 



ria dispar 



pupse 



eaten. 



Total. 







eaten, 



eaten, 









fourth to 



fourth to 









sixth 



sixth 











stages. 



stages. 









1910. 











4526- AC. 



Aug. 15 



5 



54 



3 



62 



4526- A E . 



...do.... 



4 



38 



1 



43 



4526-AF.. 



...do.... 



4 



51 



2 



57 



4526-AH . 



...do.... 



2 



49 



2 



53 



4526- AI . . 



...do.... 



4 



63 



i 



68 



4526-AJ.. 



...do.... 



4 



37 



3 



44 



4526-AK . 



...do.... 



4 



53 



1 



58 



4526-AL. . 



...do.... 



4 



45 



2 



51 



4526-AM . 



...do.... 



4 



67 



2 



73 



All the larvae cited in Table 28 died on becoming full-grown, 

 except No. 4526-AK and No. 4526-AM, one of which escaped from 

 the jar whereas the other pupated. The principal reason for the death 

 of the larvae was that the walls of their cavities for pupation collapsed. 



The average number of caterpillars and pupae required by each 

 larva for food was 57. One caterpillar of Estigmene acrsea or one 

 pupa of Porthetria dispar is equal in sustenance to two or three 

 caterpillars of Hyphantria cunea,^ and on that basis the average amount 

 of food would be 25 to 30 medium-sized caterpillars. This number 

 conforms very closely to the number consumed in 1911 when cater- 

 pillars of medium size were used. 



HABITS OF LARVyE. 



Some experiments were conducted to ascertain whether these 

 larvae will climb trees to obtain food. (PI. III.) 



The experiment was started August 15, 1911, with two first-stage 

 larvae. They remained in the experiment two days, but did not 

 attempt to climb. One larva was placed on the tree and climbed 

 upward about 6 inches before falling. 



