157 



the Liverpool district and 1 in Delamere Forest, Cheshire, 2,500 trees 

 were examined up to a height of 25 feet for breeding-places of Anopheles 

 plumheus and Ochlerotatus geniculalus. A total of 83 holes and 51 

 forks and clefts containing water were found ; 16 breeding-places of 

 A. plumheus and 19 of 0. geniculatus were discovered ; larvae of 

 A. plumheus and 0. geniculatus were associated on 13 occasions. 

 Breeding-places of A. plumheus occurred in 0*64 per cent, of the trees 

 examined and in 19-2 per cent, of holes containing water. 



Up to a height of 6 feet from the ground, 39 places containing water, 

 4 breeding-places of A. plumheus and 6 of 0. geniculatus were found ; 

 above 6 feet, 95 places containing water, 12 breeding-places of 

 A. plumheus and 13 of 0. geniculatus were found. 



Elms, horse-chestnuts and sycamores provided the great majority 

 of the breeding-places ; oaks, Spanish chestnuts and firs provided no 

 breeding-places and very few holes containing water. 



Merili*at (L. a.). Fly Repellent.— ^mer. Jl. Yet. Med., Chicago, xv, 

 no. 7, July 1920, p. 333. 



The following mixture is advocated as a fly repellent during surgical 

 operations and in the treatment of sick animals worried by flies :-- 

 lib. of common laundry soap boiled in 4 U.S. gals, of water until 

 dissolved and then mixed with 4 oz. of naphthaline dissolved in 1 U.S. 

 gal. of crude petroleum. This is best applied with a brush or sponged 

 over the hair with a sponge or cloth. 



Harrison (W. T.). Plague in California Ground Squirrels.— iH^/zt?/, 



Bull. Cal. State Dept. Agric, Sacramento, ix, no. 5-6, May- June 

 1920, pp. 187-194. 



Plague was first discovered in Calif ornia in 1900, and the first 

 epidemic of pneumonic plague to occur in the Western hemisphere 

 broke out in Oakland in September 1919, as the result of one of j the 

 inhabitants shooting squirrels in the neighbouring hills and bringing 

 them home and preparing them for food. The epidemic resulted in 

 the death of 14 persons. The Public Health Service has maintained 

 eradication measures against ground squirrels since 1908, their extent 

 being limited by the appropriation allowed. The chief reason why so 

 few cases of pla^^e have been contracted from ground squirrels is^that 

 where squirrels are plentiful there are usually few inhabitants. It is 

 not possible to estimate how complete squirrel destruction must be in 

 order to eradicate plague ; in cities 75 per cent, destruction of.* rats 

 causes plague to disappear, but this does not seem to hold good for 

 squirrels. Whether re-infection from surrounding areas takes place 

 or whether infection persists in a chronic form in a few squirrels has 

 not been determined. Plague is most acute among the young squirrels 

 in the early spring and summer months, becoming more chronic as^they 

 become more vigorous. Many carloads of carbon bisulphide and many 

 tons of poisoned barley have been used in California during the past 

 year, but much continuous work musi) be done before squirrels cease 

 to be a menace. 



