lOO REPORTS ON INVESTIGATIONS AND PROJECTS. 



REPORT OF MR. F. E. LUTZ. 



The work outlined in the last report has been conducted on as large 

 a scale as circumstances permitted. The principal insects used have 

 been Hyphantria cumea (fall webworm), Gryllus sp. (cricket), and 

 Crioceria asparagii (asparagus beetles). As in former years, trials have 

 been made of other species to determine their fitness for the work in 

 hand, especially their adaptability to laboratory conditions. In arranging 

 these conditions the aim has been to devise schemes which will, as nearl)'- 

 as possible, make the pedigree insects take care of themselves. 



The chief point in the work with Hyphantria cumea was originally to 

 test the inheritance of the dichromism of the larvse which is so generally 

 figured. The two forms, however, were not found distinct. The facts 

 of the case seem to be that the larvse reach their full pigmentation very 

 slowly after each molt, and the presence of a large number of newly 

 molted, partly pigmented larvse in a nest containing also fully pigmented 

 individuals has given rise to the notion of light and dark forms. Only 

 one individual, out of several hundred that were watched, pupated before 

 the full pigmentation after the last larval molt was reached. This was 

 probably a pathological case. It died as a pupa. Individuals may be 

 found, however, which are normally light throughout larval life. This 

 phase of the experiment has not been abandoned. Meanwhile attention 

 is being paid to the color variations of the adult which are considered by 

 some to constitute differences of specific rank. 



The biometric studies of Gryllus have been continued. It is hoped 

 that they may be valuable in themselves, but more so as a basis for 

 experimental work on the inheritance of fluctuating variants, provided 

 the technique of breeding Gryllus can be mastered. The pedigree strain 

 was all but lost this season through ignorance of the fact that the over- 

 wintering eggs almost require freezing for their proper development. 

 No time was gained by "forcing" the hatching and much material was 

 lost. Those individuals which did mature, of the lot hatched in January, 

 matured only several days earlier than their cousins which had passed 

 the egg state out of doors and hatched in June. Selection and different 

 methods of forcing will, nevertheless, be tried, both for their theoretical 

 interest and the practical importance of getting a rapidly breeding strain; 

 but the majority of the eggs will be kept this winter under perfectly 

 normal conditions lest the strain developed during the past several sum- 

 mers be entirely lost. The above remarks apply to the native Gryllus. 

 Gryllus donicsticus has also been experimented with and has multiplied 

 very satisfactorily under severe laboratory conditions. Pedigree cultures 

 have been started. Crosses between Gryllus domesticus and our native 

 crickets proved sterile, as expected. 



The main work of the summer months has been with Crioceris asparagii. 

 They hibernate as adults and become active at Cold Spring Harbor 



