SB 

 818 

 C578 

 ENT 



No. 69. 



uiiited States Department of Agriculture, 



BUREAU OF ENTOMOLOGY, 

 L. O. HOWARD. Entomologist and Chief of Bureau. 



SOME INSECTS AFFECTING THE PRODUCTION OF RED CLOTER SEED. 



By F. M. Webster, 

 hi Charge of Cereal and Forage-plant Insect Investigations. 



Our knowledge of the two insects here given more special considera- 

 tion — the clover-flower midge and the clover-seed chalcis — is still some- 

 what obscure, and particularly so in the case of the latter. In the follow- 

 ing pages the effort has been made, not so much to present a finished 

 treatise as to place within reach of the practical farmer, in a condensed 

 form, all available information relative to some of the insects that, in 

 one way or another, affect red clover seed. At the present time culti- 

 vation of this valuable crop for seed is frequently attended hy losses, more 

 or less serious, or even by total failures, the causes of which are not at 

 all well understood by the agriculturist. Bumblebees, or some similar 

 agency, are necessary to the pollination of the clover blossom. It is 

 possible, however, that many failures of the seed crop heretofore attrib- 

 uted to a scarcity of bumblebees may in reality he due to the destructive 

 work of the insects herein described. 



These two insects have been selected both because of their economic 

 importance and also on account of their interrelations, not only with 

 each other — as the presence of one in a floret precludes the existence of 

 the other — hut also with other clover insects. 



RELATIONS OF THE TWO INSECTS. 



What has until very recently been termed the clover-seed midge is in 

 all probability not a seed-infesting insect at all. but one which attacks 

 the ovaries, probably destroying them before they are fertilized, and 

 certainly before seeds can develop. The clover-seed chalcis lives in 

 the seeds only: therefore, when the first occurs it is impossible for the 

 second to exist. 



INTERRELATIONS WITH OTHER INSECTS. 



No influence of the bumblebee can produce seed where its visits to 

 the florets have been anticipated by the maggots of this midge. Bui 

 the complication does not end here by any means. Another insect, the 

 clover-leaf weevil 1 (!i.u r . l),a hectic introduced into this country by acci- 



1 Phytonomus punctatus Fab. 



