80 LIFE HISTORY OF NORTH AMERICAN TICKS. : 
A nymph molted in June in 25 days, when the mean temperature — 
was 82° F. A total effective temperature of at least 955° F. was 
required. Thus an exceptionally high effective temperature appears | 
to be required for the nymphal molt. There is also a considerable 
variation in the periods in which the nymphal molt takes place. 
The length of the molting period of nymphs which become males is 
practically the same as that for nymphs which transform to females. 
TaBLE XIX.—Molting of nymphs of Ixodes scapularis. 
[¢=Male. 9=Female.] 
Nymphs molted—days following Number | Temperature from 
2 dropping to date 
Date en: dropping. molted. first tick molted. 
gorged Num 
nymphs Host. |"jye 3 : © pb, 
dropped = . eH rs A g eel a 
25|30|34/36/38|42| 43| 50| 52/56/53 |g|s] Xe | 88 B34 
S —_ > 
sif&lea|s8@]s8 |4 
; a Ron ip 
June 23,1908 | Bovine.. | eee ee tO) a ees store eck Me eat Ke O} 24 D95.07) 70:5.) .eaeae 
June 25,1908 |...do....- 3 [fae ed1 22 SILO Aas ete OSE lct | aa 24 -3-] 95.0 | 70.55). S28ge 
June 26,1908 |...do....- 1) pA ea CE Tee (eee PSG one) esc Pee 1 1 94.0] 70.5] 82.20 
June 27,1908 |...do..... Aas. Dest Clee ae ee sabes Lea Cesar il 4} 95.0 70.5 | 82.75 
June 28,1908 }...do..... el ee | TR ee Seve ||) VO Para | ee eaceee| See s | ee e 0 if L 9520 70.5 | 83.45 
July 15,1908 |...do..... 1 ee eel eel ee ecw ioe POUL CP st Shee ae 0 1 1 99.0 73.0 85. 28 
July 16,1908 |...do..... Hil Pages| eee Pipette le | PO 1 RO) ee eee I ae 1 1 2 99.0 73.0 85. 76 
Total). 4.2. rE [tpl iat [ig oS al Ma S| at 5| 8| 13 
The adult-—The longevity of unfed males and females has not been 
determined owing to the limited supply of adults at hand. When 
removed from a host the adults do not live long unless kept quite 
moist; even the engorged females die unless they are kept under 
such conditions. 
Males and females which would not attach when placed on a host — 
September 1 attached readily when given an opportunity 4 days © 
later. The following day they were found mated. On the morning — 
of the second day the males had detached, but in the afternoon they 
were again paired. One male remained with a female for 4 days, 
while others changed to a second mate during this time. Our obser-_ 
vations indicate that ordinarily mating is not continuous upon the 
host. It appears that mating may also take place off the host. We 
have observed an engorged, unattached female and an unattached 
male in coitu shortly after they were taken from the hair of a bunting 
dog. In the course of this act the mouthparts of the male are intro- 
duced into the genital pore of the female. | 
A partially engorged female, collected in Florida, engorged and 
dropped on the seventh day after attachment to a bovine at the 
laboratory. A female applied to a bovine September 1 attached 4 
days later and remained attached until September 25, when it was 
rubbed off by the host. At that time it was about one-third engorged, 
measuring 4 by 2.2 by 1.4 mm. A second female attached at the 
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