THE BLACK-LEGGED TICK. 79 
The larva (Tables XVI, XVII).—Larve which hatched in March 
have lived for 24 months in the laboratory and then attached to a 
bovine and engorged. Their longevity is undoubtedly considerably 
longer than this period. 
Larve Were found to engorge and leave the host as soon as 8 days 
after application, the longest period required being 9 days. 
TaBLE XVI.—Engorgement of larvxe of Ixodes scapularis. 
Larve dropped engorged—days fol- | Total] 
lowing application. num- 
Date larve applied. Host. ber 
| drop- 
ee em esm lA em eon lie |e Sale On lmneds 
MS Wy Ut Mee Sopp aed geen OSC Sp Sec Rc HUG BeReE Bee ine.. TENA al ONO) | 0} 0 35 
May 23, 1908 Ou Pta |b con teers eae S| at 34 
May 6, 1909........ 2A TE WON eal OO 3 
May 11, 1909 1 Ol WH Ol Oy Wilh we 1 
In May at a mean temperature of 77.19° F. engorged larve have 
commenced to molt on the twenty-third day, the last to molt shed- 
ding its skin on the thirty-first day. Thus an accumulated effective 
temperature of 786° F. was required. 
TaBLE XVII.—Molting of larvx of Ixodes scapularis. 
Larve molted—days follow- ape ko eee 
ing dropping. Total first tick molted. 
Date engorged larve Nua ; 
2 ——— | ume 
dropped. Host. pare | | | ber a | 
molted. is _- |Average 
? Maxi- | Mini- =a 
23 | 24 | 25 | 26 | 27 | 28 | 29 | 30| 31 mel ane | cay 
| | | 
fees | alpen seal selmi te leap eet 
ag Hits ok: 
May 0) 1908). fescmeccs ine.. TSS Or POM ean eaatonel 1 O ie nO 14 | 88.50 | 63.00 77. 21 
May 10, 1908... hy. 20+}2/3/5/1/1;/0/8|0|]0 20 | 87.50 | 65.00 77.19 
May 11, 1908... a 5 OTs; 210; 0 (0/070) 0 5 | 88.50 | 65.00 77.62 
Mery 200190827 <2 ..).)-5.=.5|-5s d 4 |0]1]| 0] Others dead.| 0 | 0 1 | 91.50 | 69.00 80. 72 
May 30; 2008 S55. 2c2..c)/5-8 Rete 3 2020410) 0 0) 0" Ou 2 3 | 91.50 } 69.00 80. 86 
Mayol? 1908.c53 a5.) 2% see 3 1/01/0;0;0);0);0);0;0/1 1 | 91.50 | 69.00 80. 90 
Mayul4- 1900: eo 5. ccs 55) 55 2 1/0/;0/0/0);0;0/;0]0 1 | 97.00 | 47.00 86. 64 
TAGs ES ee 55 45 | 
The nymph (Tables XVIII, XIX)—A number of nymphs which 
molted in June lived 2 months in the laboratory and then attached to 
a host. Nymphs engorged and dropped as soon as the third day 
after application, the last to drop leaving the host on the eighth day. 
TaBLE XVIII.—Engorgement of nymphs of Ixodes scapularis. 
Nymphs dropped engorged—days | Total 
following application. num- 
Date nymphs applied. Host. ber 
drop- 
Peso 401 Oto |} dS: i ped. 
ERIC AMS ee te eke Seek wet chiteccee wee dan Sone Bovine.. 
ONO |: Loop cp ais 1 
COS ONE 3 ot aS ae SRP UAE dons On a Oi Od. hh yh O10 2 
0} 0} Oo] of 2] 0} Of o 2 
GL YALIS LOOSE She setich ct escscet el cctljace cise s[sec dost 
