THE PACIFIC COAST TICK. 187 
Taste LXXXVII.— Molting of engorged nymphs of Dermacentor occidentalis. 
| Temperature from 
dropping to date 
Engorged ey molted—days | Number 
P first tick molted. 
follo ping. molted. 
Date engorged - 
: 
Num-| | > 
— drop- Host. har. 3 by | z 
e = Bs = e 1og 
|13/14| 15 | 16 | 17| 18 | 19 21| 22 F = | 23 |8¢ 
siSiai = 5/26 
Pag tales «1 oe ee 
| f= | Siaje|l 3 | 3 |< 
‘sccuems tel Gaal Feel ees el ee ed es i aid ean 
1910. | ' et pis | | | | oF | oF. Bez 
June 12, p. m....! Guinea pig--..| U-..|--=|----|----]----|----|---]---|1 9]... i) 7 103 bes 90. 10 
July 22,a.m....\..... Pies! 4 = 1 cee 1 : 5 103 | 77.50, 90.19 
lf12 
July 22, p.m........- do.....----|  4)---|.-.f.--- () {39 | 1 3) 4) 98 | 66 | 0.26 
SR ile We TOE cee a wn do... <) fre pe | 2¢' 1° ie eae She nes ei | 2| 1 ‘ 103 | 79 | 90.27 
July 24,a.m....|..... do... ae ee giro] 19)...)...1...1 1) 4} 5) 103 | 79 | 90.28 
(SE ee Pea do... ieee wis UE areal ..--laltg | 3! 0 3} 103 | 79 | 90.21 
eee aes do... Pe, ale Bae ic See be he Oa 1 0} 1) 103.5 79 | 91.04 
oe ee do 7 Eel Toe & of--f-2) 2] 2] 3} 103.5] 79 | 96.38 
Aug. 2,a.M..... Rabbit........ 1 (ME see “15h Sill GEG, SE oo) th alee 0 1) 1) 103.5, 79 | 91.00 
Aug. 3,a.m..... Goines ple ri hel FA Se OES ae ae ?| 2] 1) 103.5) 79 | 90.96 
Se ee ae oe ee Ge ee ee ee Se 2} 0} 2) 104.5, 79 | 92.32 
Aug. 10, a.m....| Rabbit........ | 2 --2d a zee 2 0 | 104.5, 7 | 92. 32 
a es aig 3} Id es sat) FED ts 10} 104.5 7 : 
Aug. 10, p. m do ne 7 ig a | | | ‘ 6 57 | 92. 38 
Aug. ll,a.m....|..... do | 4 PA SF | 1] 1d (93! 19|...|...]... 31 3] 6 pee 73 | 91.32 
Aug. 11,m.noon.|.....do.........| 71d... -y Neg ) aiid 3) 2 5| 104.5) 79 | 92.44 
Bs| 1g] 1¢ a 58 
Aug. oS es ee ee 13. --|19 29 29 1g he ae ae cs 6 6 12 104.5 79 92. 13 
| 1g shol... ; ; 
ee ee ae | 12191... tighes 439 ig|19}...|... ‘ 5 9] 104.5| 80 | 91.96 
t ' 
Aug. 12, p.m | do ae ee Be ee ghee u 19 A i : 4 6| 104.5] 73 | 90.53 
Aug are oe do. dle abe. dees Me ite! ait | 1 1) 2) 104.5) 73 | 90.15 
Aug. 13, p.m....|.....do. ~ cy 19] 32 eS jon et ey 4) 1 5| 104.5] 73 | 90.15 
Aug. 15,a.m....|..... a ae Ses gh rs ae aL 8 2} 0, 2| 104.5) 73 | 89.67 
Total....| 103 -.-|.-- ----|oee| neal feo a. YY 2 es eee eee 
iy | | i 
1 The ticks which molted on this date are included with those recorded on the following day. 
In August, 1910, at a daily mean temperature of from 91.96° to 
92.44° F. molting commenced on the thirteenth day. The longest 
period from dropping to molting was 22 days. This occurred at a 
daily mean temperature of 69.36° F. The males and females began 
to appear about the same number of days after dropping. The 
weighted average molting period of 42 nymphs which transformed to 
males was 15.89 days. In the case of 40 females this average was 
16.22 days. The weighted average period from dropping to molting 
for all nymphs observed was 15.62 days. A total effective tempera- 
ture of 636.5° F. seems to be required for this transformation. 
The adult (Tables LX XXVITI-LXXXTX).—The number of males 
and females which molted from nymphs was practically equal. The 
greatest longevity which has been observed was 359 days. This record 
was made on a lot of 29 males and 29 females which molted from 
nymphs August 10, 1910. The last male in this lot died May 31, 
1911. It had lived 294 days. The females appear to have a slightly 
greater longevity than do the males; this is particularly noticeable 
