THE ROTUND TICK. 85 
recorded were shriveled and brownish and failed to hatch. Another 
fully engorged female, collected on a dog, March 29, 1910, began depos- 
iting on April 28, and deposited 130 eggs during the next 5 days. 
A few days later this female began to turn dark and soon died. The 
eggs deposited failed to hatch, thus suggesting that the tick may not 
have been fertilized. 
The minimum incubation period observed was 26 days. This 
record was made in the laboratory during September, 1909, when the 
mean temperature was 85.67° F. A maximum incubation period of 
53 days occurred during August, September, and October with a 
mean daily temperature of 84.58° F. The total effective temperature 
required for embryonic development appears to be at least 1,109° F. 
TaBLE XX.—Preoviposition, incubation, and larval longevity of Ixodes kingi. 
| 
Temperature during incuba- 
a tion. 
Mini- 
Engorged | Deposi- | Hatch- | mum 
female tion ing | incu- All larvee dead. oe pikes 
collected. | began. | began. | bation ceva y ave | Total 
period. : Max.| Min. daily ef- 
mean. | lective. 
1909. 1909. 1909. Days. Days. Sate Suis Hs °F. 
June 29..... July 25] Sept. 1 39 | Feb. 25-Mar. 30, 1910.| 177-210..} 110 | 77 89.32 | 1,806.5 
Dore. July 29)|-.-do-..<.. 25 | SA eRe Pee a ket) error ere 110 | 77 89.25 | 1,618.8 
DOs. - Aug. 13 | Oct. 4 53 | About May 1, 1910 About| 110] 66 84.58 | 2,203.7 
178. 
Wonecse Aug. 10 | Sept. 28 0) | lp Saeco 110 | 56 84.74 | 2,387 
Doueee Aug. 15 | Sept. 29 AB ais ia eee hee. ep eeeeed «oe 110 | 56 85.34 | 1,947.6 
Docte.- Aug. 18 | Sept. 24 38 | Apr. 27-July 19,1910 | 215-298..} 110 | 61 86.65 | 1,658.7 
Dos s2- Sept. 1] Sept. 26 DOA Ses sas 8 d= ele ae fain eee he of 101 | 61 85.67 | 1,109.4 
1910. 1910. 1910. 
Mar. 29..... Apr. 27 | June 17 52 | Before Sept. 25, 1910.| 100.....- 100 | 62.75 | 75.36 | 1,682.7 
D5 OEY ee ae May 16] June 24 AQ sess = dase - Sey; = Seek [Re peers. 100 | 60 80.61 | 1,504.4 
YN (ieicrceis June 1] July 14 44| Feb. 8, 1911_........ 1 eee 100 | 66 84.51 | 1,826.4 
June 18... .- July 5} Aug. 5 323) Hebr4, JO1l se <5 32. IBS See 104 | 73 88.09 | 1,442.9 
The larva (Tables XX—XXI).—The larve of this tick have been 
found to live at least 215 days. The lot upon which this record was 
based hatched September 24, 1909. Fifty were still alive April 27, 
1910. Other lots hatched in midsummer were found to live nearly 
as long as the one cited. Larve may drop engorged as soon as the 
fourth day after application to a host, while some may remain on the 
host 16 days and even then not become fully engorged. Although no 
engorgements were obtained from two or three lots of larve applied 
to bovines and guinea pigs, most of the lots tested attached readily 
and a large percentage of them engorged. Attachment was found to 
take place usually within an hour after the time of application to a 
host. Many specimens were found detached from the host when they 
were from one-fifth to two-thirds engorged. This premature drop- 
ping is probably due to the ease with which they are displaced by the 
host animal after they have become partially engorged. 
