Oct, 19, 1888.] 



SCIENTIFIC NEWS. 



**3 



starved cat, which had taken up its quarters at the 

 Academy, was seen on the roof. Quite near it, and close 

 to a nest, two pigeons were resting, quite ignorant of the 

 danger. But instead of seizing the birds, pussy waited 

 till they flew away, and then advancing very carefully she 

 reached the edge of the roof, thrust her paw under a 

 tile, raised it gently, and looked down into the nest. 

 With our opera-glasses we could see the eggs, and ex- 

 pected that she would break the shells and devour the 

 contents. Not at all ; she made a conscientious review of 

 all the nests, and went away very philosophically. For 

 a week, at sunset, this proceeding was repeated ; the cat 

 arrived punctually, made her visit of inspection, and 

 departed. One fine day we could see young pigeons 

 in most of the nests. The visitor came as usual, ex- 

 amined everything, and again departed. One of us said, 

 laughing, " She is waiting until they are in good con- 

 dition." Such was the case. In a few days the marauder 

 lifted up a tile, and did not replace it ; she thrust her 

 head into the hole, and reappeared, holding a young 

 pigeon, which she devoured forthwith. This is not all ; 

 so methodical was the cat that she never took more 

 that two pigeons, but one evening, when she was about 

 to seize her dinner, the coveted prey sprung from the 

 nest and flew away. The cat took an attitude of indefinable 

 stupefaction, but soon recovering she made a complete 

 raid under all the tiles, and in the morning we found in 

 the bell-tower the remains of ten young pigeons. 



Cockchafers in Autumn. — M. Dufeu (La Nature) 

 states that he has this year found cockchafers during 

 the month of September, their usual time of appearance 

 being in May. When digging in his garden at Varenne- 

 Saint-Hilaire (Seine), he has just found one at the depth 

 of eight inches. 



THE SHEEP FLY (LUCILIA SERICATA). 



SEVERAL instances are known of a change, gradual 

 or sudden, in the diet of an animal species not by 

 any means due to a deficient supply of what the older 

 zoologists would have called its " natural food." Semper 

 relates in his work on " The Conditions of Existence of 

 Animals," that sea-gulls have been known to cease prey- 

 ing upon fish and feed upon grain. On the contrary, 

 bats have in South America taken to fishing instead of 

 pursuing moths. 



The New Zealand parrot (Nestor mirabilis), formerly 

 nourished itself on the juices of plants and flowers, but 

 has now developed an amazing propensity for sipping the 

 blood of sheep. .The blue-nosed baboons of South Africa 

 are occasionally guilty of killing and devouring sheep. 



Similar changes of habit are met with more fre- 

 quently in insects. Considerable attention has been 

 latterly attracted to a small carrion-beetle (Silpha alrata) 

 which has turned vegetarian, and proves very destruc- 

 tive to the mangel wurzels and sugar beets. A very 

 curious case of this kind is described by Ritzema Bos, 

 in the Biologisches Centralblatt and the Naturforscher. A 

 well-known fly (Lucilia sericata) has become a dangerous 

 parasite of sheep, by a change in its food during the 

 larval stage. 



Like the maggots of many Muscidce the larvae of 

 Lucilia sericata generally lived in dung, or in the flesh of 

 dead animals. Karsch considers the species in question 

 as a genuine blow-fly, whilst Ritzema Bos has found its 

 larvae able to live in sheep's dung. In many districts of 



the Netherlands, the maggot now infests the flesh of 

 living sheep, and in seasons favourable to its develop- 

 ment, it occasions a really formidable epidemic among 

 them. This new plague is most to be dreaded in the 

 luxuriant marsh-pastures of North and South Holland, 

 Friesland, and Groningen, whilst on poor, sandy, and 

 heathy soils the sheep suffer little. According to Ritzema 

 Bos the flies are induced to deposit their eggs in the ex- 

 crement which often adheres to the wool of sheep. Less 

 frequently do they attack parts of the animal which are 

 free from such impurity. In ovipositing, the fly alights 

 upon the body of the sheep and fixes its eggs to the 

 wool in groups of ten to twenty, until about 500 have 

 been deposited. Their development depends on the 

 weather, but it takes from twenty to forty hours, when 

 the maggots, closely resembling those of the blow- fly, 

 creep out and reach their full growth in from fifteen to 

 twenty-four days. The larva? then leaves the body of the 

 sheep and falls to the ground. Here it remains lying 

 among the grass of the pasture, and is transformed into 

 a pupa. Several generations succeed each other in the 

 course of the summer, and the larvae of the lastgeneration 

 probably creeps into the ground and pass the winter 

 their as pupae. 



The symptoms of the disease produced in sheep by 

 these larvae depend firstly in the irritating action of the 

 larvae upon the skin. The skin then secretes a serum- 

 like, offensive liquid, which gives the wool a bad colour, 

 and makes the hairs adhere together. The skin, in con- 

 sequence of the grubs creeping over it and boring into it, 

 becomes hot, of a blood-red colour and swollen. When 

 the mature parasites have left the sheep, the superficial 

 inflammation heals, though the wool falls off in conse- 

 quence of the elimination of the thickened layers of the 

 epidermis. Most commonly, however, the injury 

 occasioned by the first brood of maggots is intensified by 

 those of the following generations, and as there are flies 

 all the summer which deposit their eggs, the disease 

 grows constantly worse. It extends not merely forwards 

 from the hind-quarters of the sheep, but the larvas pene- 

 trate deeper and deeper, not merely into the subcutaneous 

 cellular tissues, but into the muscles, which they mine 

 and consume. 



The occurrence of this maggot-disease in the Nether- 

 lands cannot be traced with certainty, though it seems 

 to have been first observed about i860. An alleged 

 introduction from England (!) cannot be demonstrated, as 

 the disease attacks all races. It is rather to be assumed 

 that the fly, which is a native of the continent of Europe, 

 has assumed parasitic habits in the Netherlands in the 

 manner already described. Hitherto sheep have not 

 been attacked in this manner in Germany. This deserves 

 notice, as the fly, which is described as rare by Karsch, is 

 now very common in North Germany, Whilst the zoolo- 

 gical collection in Berlin till lately possessed only two 

 specimens from Styria, it is now caught freely on putrid 

 flesh laid as a bait. Hence the question arises whether 

 Lucilia sericata, as well as Sarcophila wohlfahrti, may not 

 be concerned in the numerous cases of Myasis in man 

 which have been observed in Europe. 



The common lurid green Lucilia ccesar and Lucilia 

 sericata, likewise of a green colour, are distinguished 

 chiefly by the position of the eyes in the male. In L. 

 ccesar they almost touch on the head, whilst in L. sericata 

 they are separated by a black line. The females are 

 distinguished by the frontal line, which in L. ccesar is 

 black, but in L. sericata grey-brown and narrower. 



