40 



Bergmann (A.). Om renens oestrider. [On the Bot-flies of the 

 Reindeer.] — Ent. Tidskrift, Stockholm, xxxviii, 1917, pp. 1-32, 

 113-146, 26 plates. 



After an introductory description of the adults and full-grown larvae 

 of Oedemagena tarandi, L., and of Cephenomyia trompe, L., the author 

 gives a detailed account of the egg, the egg-laying habits, the three 

 different larval stages and the pupa of 0. tarandi. The behaviour of 

 reindeer when attacked by this fly, and the abscesses caused by its 

 larvae are also described. 



The eggs are attached to the hairs and are often placed in rows of 

 6-10. Oviposition takes place from the middle of July to the beginning 

 of vSeptember, at a period when the winter hairs of the reindeer are 

 not completely shed. The female in ovipositing sits on the winter 

 hairs and with the help of its long ovipositor places the eggs on the 

 new and shorter summer hairs. Examination of a reindeer calf dis- 

 closed the existence of 329 eggs on it, distributed on all parts of the 

 body with the exception of the head, the middle of the back, the 

 chest and the belly. The number of eggs laid by a single female was 

 ascertained by dissection to be nearly 500, and this represents the 

 minimum number, as the dissected females may already have deposited 

 some eggs. The females seem to prefer white hairs, white animals 

 being invariably more attacked than others. 



Reindeer are very sensitive to the attacks of these bot-flies, becoming 

 very excited when the flies alight on them and wandering about in a 

 restless manner from 7 a.m. to 8 p.m., when the flies are on the wing. 



An examination of reindeer calves in the autumn showed that the 

 young larvae enter the surface of the skin, and at the end of the first 

 stage, when they have attained a length of 7-9 mm., penetrate the 

 skin, where an opening appears, 0-5 mm. in diameter. The warbles 

 are chiefly to be found in the flanks and hind quarters. No animal 

 was ever found entirely free from them except when it had been kept 

 in a zoological garden over a year. The smallest number recorded was 

 60, and the greatest, 318. From the middle of May the larvae drop 

 to the ground in order to pupate, hiding in the moss. The pupal 

 stage lasts 27 daj^s on an average. 



Cephenomyia trompe is viviparous, and the young larvae of the first 

 stage are found in the nostrils ; later on they enter and penetrate the 

 nasal sinuses. Dissected females contained up to 580 larvae. The 

 larvae cause inflammation, and sometimes wander into the lungs of 

 the host, causing its death. When full-grown, the larvae cause violent 

 sneezing in the animal and are thus ejected ; this takes place from the 

 middle of May, the pupal stage lasting about 19 days. 



The economic importance of these flies is very great, nearly every 

 reindeer being more or less infested by them. As above mentioned, 

 Cephenomyia trompe may occasionally cause the death of its host, and 

 both insects cause great suffering to the animals and by continually 

 disturbing them when grazing, prevent their growing fat. Moreover, 

 the hides are much damaged, skins of reindeer killed from February 

 to July having very little value, which is one of the reasons why the 

 animals are killed in late autumn. 



Of the two pests, Cephenomyia is the more difficult to control, 

 owing to the position in which the larvae occur. The author suggests 

 that capturing the adults with nets when they hover round the herds 

 would be useful, if the children of the Laplanders could be educated 



