48 THE SUGAK-BEET WIREWOEM. 
than 0.1 per cent were affected by it in the field. These two checks 
are of very little importance. 
Enemies and Checks to the Larv^. 
Two characteristics of the Avireworms, their thick skins and their 
underground Hfe, cause them to be almost free from enemies. Of the 
10,000 larvae collected not one was noticed which was attacked by an 
internal parasite, although such parasites have been reported attack- 
ing Elateridse. Curtis ^ reports an ichneumon parasite en wdreworms 
in Great Britain, and says that Bierkander (of Sweden) also found 
them. Dr. S. A. Forbes ^ reports a single instance where a parasitic 
fly was reared from a wireworm. Very probably there are no eflacient 
parasites in this group. 
The sugar-beet mreworm is, however, eaten readily by several 
kinds of birds whenever exposed. During the spring, when several 
of the fields at Dominguez, Cal. (6 miles from the ocean), were being 
plowed, it was noted that sea gulls (Larus sp.) were very abundant 
in the fields and followed the plow much as chickens do. They 
occurred by the hundreds and, as they are known to be omnivorous, 
they must have eaten numbers of wireworms. At this time and 
earher crows were also very abundant in the beet fields. During 
this period the wireworms were feeding at the surface on the left- 
over beets, and it was easy for the crows to reach them. As crows 
are famed as wireworm destroyers it is only reasonable to suppose 
that they killed large numbers of the larvae. This point ^\dll be 
investigated thoroughly in the future work on this insect. 
Larvae of a large carabid, probably Calosoma cancellatum Esch,, 
have been found in the ground together ^Aith injured wireworms. 
In addition to bird and insect enemies one fungous and two bacte- 
rial diseases have been noted on this mreworm. The fungus is only 
observed occasionally in the field, hence it is probably of little impor- 
tance economicaUy. The bacterial disease of the mature larva was 
especially disappointing, as it seemed to work only in certain cages. 
This naturally led to the belief that its presence was probably more 
the result of unfavorable conditions than the cause of them. The 
bacterial disease of the young larva did not promise much, as it did 
not seem to attack mature larvae under any conditions. 
As has been mentioned under the headmg ^'Rearing cages used" 
(p. 21), many of the young Avireworms which were kept in petri dishes 
died of a bacterial disease. This disease spread very rapidly, and 
there seemed no way to check it. Wherever it appeared, all the 
healthy wireworms were removed to a sterile cage and the infected 
cage steriUzed. The cages were examined several times a day and all 
1 Farm Insects. By John Curtis, IStiO, pp. ISl. 2 ISth Rept. State Ent. 111., pp. 47, 1891-92. 
