June, '22 mccolloch: length larval stage of cadelle 241 



Herrick-^ (p. 234) discusses the observations made by Slingerland, who 

 reared this insect in wheat under insectary conditions. He found the 

 egg stage to be about ten days and the larvae lived from August to the 

 following April and May. He concludes from these observations that 

 the life cycle is about one year. Slingerland also found the adults to 

 be longlived, one beetle living nearly a year. Zvierezomb-Zubovsky ^ 

 reared the Cadelle in flour and found it to have one generation a year. 

 The egg stage varied from 7 to 24 days, the larval stage from 98 to 115 

 days, and the pupal stage frm 8 to 30 days. He states that adults 

 emerging in the fall probably hibernate as do the larvae hatching late 

 in the season. Throughout the most of the literature on economic 

 entomology, this species is said to require one year for its life cycle. 

 It is not the purpose of this paper to give an extended account of the 

 life history, but rather to record certain observations, especially on the 

 longevity of the larval stage. During the past few years the writer 

 has had a ntLmber of Cadelle under observation and while the data are 

 meager they are suggestive and indicate the need of a more extended 

 study of this injurious species. 



These studies were begun Sept. 7, 1916, when two larvae, each about 

 one-eight of an inch in length, were found in a sack of seed com. These 

 were placed in separate one-half ounce tin salve boxes containing 

 wheat and wheat bran for food and placed in the cave used for much 

 of the life history work at the Kansas station. •'" One of these lived 

 until July 30, 1918, and the other until August 23, 1919. This prolonged 

 larval life was of such interest that it seemed advisable to obtain newly 

 hatched larvae for futher work. 



During July and August, 1918, several adults were placed in cages 

 .and 26 eggs were secured. These eggs hatched in from 15 to 18 days, 

 and the larvae were placed in salve boxes as has been described. Ten 

 of these larvae died during 1918, three in 1919, eight in 1920, and two 

 in 1921. One larva is still alive at this writing (Dec. 15, 1921). In 

 addition to these larvae, a namber have been collected at various times 

 and placed under observation. 



As has been mentioned, the extended life of the larvae has been of 

 special interest. In the case of the two worms collected Sept. 7, 1916, 



^Herrick, G. W. 1914. Insects Injurious to the Household and Annoying to 

 Man. The Macmillan Co., New York. 



''Zvierezomb-Zubovsky, O. 1919. On the Biology and Morphology of Tenebroi- 

 des mauritanicus L. Report on the work of the Don Bureau for the Control of Pests 

 of Agricultural Plants for 1918. RostofF. Abstract in Rev. App. Ent., Vol. 8, 

 Ser. A. pp. 107-108. 



^McColloch, J. W. 1917. A Method for the Study of Underground Insects, 

 lourn. Econ. Ent., 10: 183-187. 



