Larval parasites ofOulema melanopus in Europe and their colonization in the United States

The cereal leaf beetle,Oulema melanopus (L.), of minor economic importance in Europe, was found in Michigan, USA, in 1959, and has caused increasing damage to small grains. Studies in Europe prompted the introduction into the United States, of 3 hymenopterous parasites of the larval stage:Tetrastichus julis (Walker),Diaparsis carinifer (Thomson), andLemophagus curtus Townes, as a multiplespecies biological control attempt. From 1964 to 1970, field collections in 10 European countries showed that parasitism averaged 12.3% byD. carinifer, 10.4% byT. julis, and 5.6% byL. curtus. Parasites are discussed with respect to life-history, distribution, constancy, hostrange, synchrony with host, and effects of encapsulation by the host larva. Techniques are described for parasite collection, rearing, shipment, overwintering in quarantine, field release, and recovery. Adult parasite releases in the USA (1964–1971) totaled 43,054D. carinifer, 31,123T. julis, and 3,109L. curtus. BothD. carinifer andT. julis are known to be established at several sites in Michigan, andT. julis is also established in Ohio.Lemophagus curtus was recovered in Michigan in 1972.