560 EXPEEIMEKT STATION EECJOBD. 



although many of them lived 20 days or longer, while control flies fed on blood 

 did lay eggs. 



" The incubation period in eggs kept at from 16 to 25° C. (from G0.8 to 77° F.) 

 varied from 2 to 5 days and was commonly 3 days. The newly hatched larvae 

 buried themselves in the breeding material, being strongly negatively helio- 

 tropic. The larviE required much moisture. They grew slowly, compared to 

 house fly and flesh fly larvae, reaching full growth in from 14 to 26 days 

 (usually about IS), depending on moisture, light, and temperature. Before 

 pupation the larv£e crawled up into the drier layers of the decaying vegetable 

 matter in which they developed and became pupse in less than 1 hour after they 

 had begun to change. We found the pupal period at from 23 to 26° C. to vary 

 from 6 to 26 days, but usually to lie between 9 and 13 days. 



" The total time at 21° C. from the laying of the egg to the hatching of the 

 adult fly was from 33 to 36 days, as observed in 5 individuals. 



" The length of life of the flies under the favorable conditions of feeding in 

 our principal experiments was on the average 20 days. The maximum was 69 

 days, and was observed in a female fly." 



Poliomyelitis. — Further attempts to transmit the disease through the 

 agency of the stable fly (Stomoxys calcitrans), J. F. Andeeson and W. H. 

 Frost {Pub. Health Rpts. [U. S.], 28 {1913), No. 18. pp. 833-837).— The authors, 

 having carried out several series of more extended experiments than those 

 previously noted (E. S. R., 28, p. 161), report that the results of all later ex- 

 periments, contrary to their expectations, have been entirely negative. Up to 

 the time of writing they had found no satisfactory explanation for this dis- 

 crepancy. 



A study of the biology of the apple maggot (Rhagoletis pomonella), to- 

 g'ether with an investigation of methods of control, J. F. Illingwobth {New 

 York Cornell Sta. Bui. 324, pp. 129-187, pis. 13).— This bulletin is based upon 

 studies commenced in 1910 and carried on through the entire seasons of 1911 

 and 1912. The subject is dealt with under the headings of methods of work, 

 history of the apple maggot, seriousness of the pest, other fruit flies, life his- 

 tory and habits, technical description, methods of control, etc. 



The principally infested districts extend from New Brunswick, Quebec, and 

 Ontario, south to Pennsylvania, with a single record from North Carolina, west- 

 ward to Iowa and Wisconsin, with brief mention in Minnesota. South Dakota, 

 and Colorado. Under host plants the author includes a revised list of apple 

 varieties, showing their relative infestation. The author has found no variety 

 that is known to be immune, although the hard winter sorts soften so little 

 before cold weather comes on that probably most of the larvae fail to develop. 

 Haws and wild crabapples appear to have been the original foods. Subsequent 

 records show cultivated fruits to be attacked, principally apples, although pears, 

 cultivated crabapples, and huckleberries are also included. 



In the vicinity of Ithaca the flrst-brood flies appear to emerge from the middle 

 of June up to August 1, and there are second-brood flies which begin emerging soon 

 after the latter date, so there is an almost continuous new supply of flies from 

 June up to the time of heavy frosts. Twenty Bough apples examined showed from 

 11 to 36 egg punctures each. Flies reared in cages mated from the eighth to tenth 

 day after emerging and oviposited on the twenty-fourth day. The eggs were found 

 to hatch in from 2 to 6 days. " The growth of the larva varies greatly. Under 

 the most favorable conditions, a ripening fruit and warm weather, the larva 

 may be fully developed and emerge within two weeks from the time that the 

 egg hatches; while if the fruit is very hard and green or the weather cold, 

 growth slows down and the time of emergence is put off for months. ... In 

 only one case has the writer found that the larvae leave the fruit while it is 



