PREVIOUS WORK WITH INSECT PARASITES. 
k 21 
Fig. 1. 
■Polygnotus hiemalis, a parasite of the Hessian By: 
Greatly enlarpe.l. | From Webster.) 
Adult. 
portation from one part of the country to another becomes easy, since 
all that has to be done is simply to collect twigs bearing the scales, 
preferably during the 
winter months, and 
carry them to non- 
protected regions, 
the parasites being 
dormant and pro- 
tected each by the 
scale of the coccid 
which it had de- 
stroyed; and it was 
specifically recom- 
mended that the im- 
portant parasite of 
the black scale {Safe- 
st tin <>h n Bern, i, de- 
scribed in the article 
a< TimuH'irn culifor- 
nic&j could he readily 
carried from California and utilized to destroy Lecaniuni .scales 
in the Southeast. 
Ivxcellent work in this direction ha been done of 
late years by the Bureau of Entomology. In the study 
of the Hessian fly {Mayeticla destructor Say), under 
Prof. F. M. Webster, early -sown plats of wheat at 
i^. 0< Lansing, Mich., and Marion. Pa., in 1906, were very 
seriously attacked by the BEessian fly, but when ex- 
amined carefully at a later date fully 90 per cent of the 
flaxseeds (pupa) were found to have been stung by a 
hyinenopterous parasite, Pohjgnatus hiemalis Forbes 
CngB, 1, 2), and to contain its developing larva?. A 
field of wheat near Sharpsburg, Md.. was found to be 
infested by the fly, and examination indicated the al>- 
sence of the parasite. On April S, 1907, a Large num- 
ber of the parasitized flaxseeds from Marion, Pa., 
were brought to Sharpsburg and placed in the field. 
On July 8 an examination of the Sharpsburg field 
showed that the parasites had taken hold to such an 
extent that of the large number of flaxseeds taken and 
brought to the laboratory for investigation not one 
was found which had not been parasitized. Additional 
material secured from Sharpsburg in the spring of 1908 
in the same locality showed all of the Hessian flies to be parasitized. 
In the same way excellent results have been obtained in the investi- 
gation of the cotton-boll weevil, under Mr. W. D. Hunter. In the 
Fig. 2— Polygnotus 
hiemalis: Adults 
which have de- 
veloped within 
the "flaxseed" 
of the Hessian 
fly and are ready 
to emerge. Much 
enlarged. (From 
Webster.) 
