Glenn, P.A. 1931 Use of temperature accumulations as an index to the time of appearance of certain insect pests during the season.. Transactions of the Illinois State Academy of Science 24: 167-180.

Notes: Paper presented in the 24th annual meeting; predictions given for number of day degrees of effective temperature before appearance of the following insects: Chionaspis furfura, C. americana, C. pinifoliae, Lepidosaphes ulmi, Aspidiotus perniciosus, Pulvinaria vitis and Gossyparia spuria.