Apr. 15, i9i8 Overwintering of the House Fly 163 



age were used. From rearing experiments in the greenhouse eggs were 

 obtained January 9, 191 5. These hatched and were carried through in 

 horse manure confined in a large wooden box. From this lot about 150 

 puparia were collected on January 26, immediately placed in a box (8 

 by 8 by 10 inches), and covered with 4 inches of dry sand. The box was 

 taken to the apicultural laboratory at Drummond, Md., and buried to 

 within I inch of the top of the box in the ground near the east wall of the 

 building. With the help of Mr. G. S. Demuth thermocouples were in- 

 serted in the sand among the puparia. The box was then covered with 

 a glass plate and over this was placed a square of rubberized roofing and 

 a large quantity of sawdust. Temperature records were taken eight 

 times daily from this date until April 26, by means of the electrical 

 apparatus used by Phillips and Demuth {16) in their work on the tem- 

 perature of the bee cluster in winter. The actual temperature to which 

 the puparia were exposed was uniformly low, but never less than 34° F. 

 There was a gradual rise in temperature until 45° F. was reached, on 

 April 26, when the readings were discontinued. On May 17 the box was 

 taken from the ground. No fiies had emerged. The puparia were col- 

 lected and examined. While their external appearance was normal, of 

 10 puparia which were dissected, 7 were found to contain a brown sticky 

 liquid, and in 3 the pupae, although well formed, were completely dried 

 up. The other puparia were kept in ordinary garden soil until July 17, 

 but no flies emerged. 



All these experiments are open to the criticism that the conditions 

 were more or less artificial, and that relatively small numbers of puparia 

 were used. Attempts to provide more nearly natural conditions and to 

 determine the possibility of overmntering in large heaps of manure were 

 first reported by Bishop, Dove, and Parman (2). They report two cases 

 in which they succeeded in carrpng the house fly through the winter in 

 the immature stages. In one of these, at Dallas, Tex., 3 barrels of horse 

 manure, cow manure, and straw were put in a cage on November 26, 

 1913. No flies emerged after December 27 until April 16, 1914, when 4 

 specimens appeared. Others emerged May 26. Larvae were found in 

 some numbers up to March 21. Thus it was shown that the house fly 

 lived in the larva stage for a period of 115 days, and in the larva and pupa 

 stages until April 16 and May 26, periods of 141 to 181 days. In a sec- 

 ond experiment, at Uvalde, Tex., horse manure and straw v/ere put in a 

 cage on December 6, 8, 9, and 13, 191 3. Emergence continued during 

 warm periods throughout the wdnter. From i to 9 flies emerged daily 

 from March i to 18, and on each of three days (Apr. 1,2, and 4) a single 

 fly emerged. Dove (5) gives further details of these experiments. 



The publication of the experiments of Bishopp, Dove, and Parman (2) 

 brought up the question whether they were paralleled under more severe 

 winter conditions, or whether they obtained only in the moderate climate 

 of Texas and the Gulf coast. Experiments similar to these were carried 



