162 



{D. venustus) , the combined attack of tliese two species, together 

 witli a shortage of feed, often causes the deathofniimhers of horses. 

 In Oregon, H. II. Ilach observed a great difference in the sus- 

 ceptibility to attack of different horses even when kept under 

 identical conditions. Such a tendency to immunity was also 

 shown by cattle. This resistance appears to be due largely to 

 an unusually strong- tendency to form scabs at the point of 

 attack, thus healing the wound and throwing off the tick with the 

 scab. It was observed that in cattle the ticks became attached 

 in numbers on the neck and along the back, particularly above 

 the shoulders and near the base of the tail. 



The third species of Dermacentor described in the present paper 

 is D. nigrolineatus, Packard, regarding the distribution of which 

 comparatively little is known. It has been recorded from the 

 Adirondacks, the Catskill Mountains, Wisconsin, Tennessee and 

 Texas. Most of the specimens have been collected from deer 

 (Odocoilevs inrginiamis texaniis), and Stiles records females and 

 nymphs from horses. The authors collected all stages on cattle 

 in Tennessee and have reared species experimentally on that host. 

 The ticks would not feed on the guinea-pig, but attached them- 

 selves to tame rabbits, though none of them became engorged, 

 probably owing to being scratched off. Like its nearest relative, 

 D. alhipicivs, this species usually feeds during the autumn, 

 winter and spring, and passes through both moults on the host. 



J). nifjrol{neatui> appears to be of little general economic im- 

 portance, although locally it sometimes infests cattle sufficiently 

 to reduce greatly their vitality and flesh. The only locality in 

 which the authors know of its occurrence as a pest is in Fentress 

 Co., Tennessee. The backs and hind-quarters of the animals are 

 usually the most heavily infested. 



MacGilchrist (Major A. C). Stegomyia Survey, Port of Cal- 

 cutta. — Proa. 3rd Meeting Gen. Malaria Covim., Madras, 

 18th to 20th ISTov. 1912, pp. 193-196. Simla, 1913. 



Two species of Stegomyia, fasciata and scutellaris, occur in the 

 Port of Calcutta, and are known to bite in the daytime. The 

 former species is a city mosquito and has not been found in any 

 of the villages on the banks of the Hooghly below Garden Reach. 

 ,S'. scutellaris is often found breeding some 100 yards away from 

 inhabited houses and is exceedingly common throughout the port. 

 The only other mosquitos that bite in the day belong to the genus 

 Desvoidya, the commonest being D. obturbans which breeds in 

 foul stagnant water. Leucomyia gelida was very common in 

 Calcutta and neighbourhood during August and September. Two 

 species of Toxorhyncliites were found extensively. A Toxorhyn- 

 chites larva can easily devour half a dozen good-sized larvae of 

 another genus in about half an hour. It was observed that indi- 

 viduals of S. fasciata not infrequently copulated with individuals 

 of >S'. scutellaris; but this crossing seems to be unproductive. 

 The breeding places attractive to these species and measures for 

 their destruction are discussed. 



