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Show Pea Insects of Utah' By GEORGE F. KNOWLTON2 The pea crop of Utah is occasionally damaged very seriously by insects. During 1936, peas were seriously affected by the pea aphid. Other insects also damage garden, field and sweet peas, and pea seed in The storage. following report deals briefly with a number of the insects and a few related pests affecting peas in Utah. Grasshoppers, when abundant, cause injury to field peas and sometimes more serious damage to garden and sweet More common species. af peas. fecting such plants are Melanoplus [emur-rubrum (De. G), M. bivittatus (Say), M. mexiconus (Saus.), M. packardi Scudder and Dissosteira carolina (L). The clover leafhopper, Aceratagallia sanginolenta (Prov.), occurs through . out Utah and regularly infests peas, as well as alfalfa and clover. The leafhopper, Empoasca filamenta DeL. and E. flavescens (Fabr.), also occur upon peas and certain other leguminous crops. The bean aphid, Aphis rumicis L., and the potato aphid, Macrosiphum solanifolii (Ashm.), occur in small numbers upon peas; however, the principal aphid injury results from the com mon pea aphid, Macrosiphum pisi (Kalt.). This species, (Fig. 1, A-E), oc curs throughout Utah wherever alfalfa or peas is grown. Occasionally there is an increased abundance of this pest which results in widespread injury. Such an outbreak caused injury to field peas and alfalfa in parts of Cache Valley during 1923 and wiped out an "infant" sweet-pea seed industry at Smithfield. The pea aphid outbreak of 1936 was the most widespread and destricutive of the outbreaks in Utah. Practically all of the approximately 13,000 acres of commercial canning peas were seriously The damaged. pea aphid feeds by preference upon tender apical growth of its host plants, but in severe outbreaks it may be found upon all parts of the affected pea vines above ground. Damage most frequently has ben severe upon sweet peas. Garden peas sometimes have been damaged when extensive injury to field peas did not occur. Control.-A ground Derris or Cube root dust of 4 per cent rotenone content should be used as a spray, 3 pounds of the dust, and lh pound of a commercial non-alkaline wetting and sticking agent (such as a dry commercial sulphated phenylphenol, sodium lauryl sulphate or sodium oleyl sulphate) being used in each 100 gallons of water. Power equipment with properly adjusted nozzles and a presure of at least 300 pounds are nec for best control. Approximately 175 essary gallons of this spray should be used to each acre. Dusts of other than 4 per cent rotenone should be diluted the above strength. This spray should be applied before serious aphid injury occurs. Biological control.-Adult and larval ladybird beetles, Hippo damia convergens G., were very abundant in affected fields, while H. quin que signata Kirby and H. parenthesis (Say), were also feeding upon the aphids in Cache, Weber and other northern Utah counties. Natural enemies did much to reduce pea aphid injury in a number of localities of northern Utah during 1936. The greenhouse whitefly, Trialeurodes vaporarium (Westw.), has been taken upon peas, but the writer never has observed it to be abundant to to cause Contribution from 2 enough appreciable damage. the Department of Entomology, Agricultural Station. Publication authorized by Director, August 20, 1937. Associate Entomologist. Utah 167 Experiment |
