162 Maine Agricultural Experiment Station. 1918. 



The setae of the pupae are formed by the same trichogen 

 cells which formed the larval setae. They are not hollow sense 

 hairs like the larval setae, but are solid and pointed. They are 

 developed only on the dorsal side, or the anterior and posterior 

 ends of the body, so that their function would appear to be to 

 hold the pupa away from contact with the sides of the pupal 

 cell, since the insect lies with the ventral aspect uppermost. 



The accessory trichogen cells (those which will not be 

 utilized in forming the pupal setae) are phagocytized during 

 the prepupal period, after the larva has entered the ground and 

 constructed its cell, so that sense hairs are of no further use 

 to it; and the trichogens which form the pupal setae are them- 

 selves phagocytized within 24 hours after pupation. The tri- 

 chogen cells of the adult hypodermis are entirely unrelated to 

 those of the pupal or larval hypodermis, so far as the writer 

 has been able to ascertain. 



Description of the pupa ready to transform. Dorsum of 

 prothorax gray ; metathoracic thickenings brown ; eyes and an- 

 tennae jet black; mandibles dark red brown, black tipped; wings, 

 tibiae, tarsi, and caudal portions of femora piceous ; elytra col- 

 orless (though they appear gray as the wings show through 

 them) ; otherwise like the newly formed pupa. 



Biological History. 

 summary of rearings. 



Length of the egg stage. A record which was kept of 215 

 eggs deposited between June 16 and July 14, inclusive, may be j 

 tabulated as follows : 



5 hatched in 7 days, 81 in 8 days, 63 in 9 days, 38 in 10 days, 9 in 11 

 days, and 19 in 12 days ; average 9 days. 



Length of the first larval instar. A record which was kept 

 of 220 larvae which hatched between June 16 and July 14 in- 

 clusive, may be tabulated as follows : 



63 molted to the second instar in 4 days after hatching from the 

 egg, 45 in 5 days, 53 in 6 days, 21 in 7 days, 17 in 8 days, 10 in 9 days, 

 and 11 in 10 days; average 6 days. 



Length of the second larval instar. A record which was 

 kept of 233 larvae which molted to the second instar between 

 June 22 and July 30 inclusive, may be tabulated as follows : 



