Catfacing by Oak and Hickory Plant 

 Bugs in Massachusetts Peach Orchards 



Kathleen P. Leahy 



Department of Entomology, University of Massachusetts 



Although there are several types of damaging 

 insects present in local peach orchards, including 

 borers, aphids, and Oriental fruit moth, most grow- 

 ers in Massachusetts are concerned primarily with 

 the complex of insects which cause feeding scars, or 

 catfacing, on the surface of the fruit. The traditional 

 "most wanted list" of catfacing insects includes the 

 tarnished plant bug, plum curculio, and three spe- 

 cies of stink bug: green, dusky, and brown. 



Recently, attention has been focused on the 

 catfacing activity of three species of the genus Ly- 

 gocoris: the white oak plant bug (L. quercalbae), the 

 hickory plant bug (L. caryae), and L. omnivagus 

 (which does not have a common name). The three 

 species are very similar in appearance and have 

 sometimes collectively been called "oak-hickory" 

 plant bugs. The genus is closely related to the genus 

 Lygus that includes the tarnished plant bug, and 

 they look quite similar to the tarnished plant bug 

 except that they lack the characteristic markings on 

 the scutellum and the "tarnished" or shiny appear- 

 ance, and look a little less sturdy. They are usually 

 brown to brownish-yellow. See Figure 1. 



These plant bugs were cited frequently in the 

 literature in the 1920s and 1930s as causing cat- 

 facing injury to peaches, but received little attention 

 between that time and the 1980s. Since they have 

 not been well studied as peach pests, and are not 

 considered pests in the forests where they spend 

 most of their life cycle, apparently little is known 

 about them. 



All three species spend most of their lives on host 

 trees in the woods - oak, hickory, chestnut, dogwood, 

 black walnut, beech, and several other tree species. 

 As adults, they disperse from their native hosts, 

 during which time they may move through peach 

 orchards. This flight usually begins in early June, a 

 few weeks after peach shuck split, and generally 

 peaks in mid-June, decreasing considerably in July. 

 They do not appear to reside within peach orchards, 

 but only visit them briefly and feed in a "hit-and-run" 

 fashion, which may make them difficult to control. 



Tarnished plant bug injury generally occurs 

 close to petal fall, and usually causes fruit drop. 



Lygocoris feeding occurs later and usually causes 

 catfacing: sunken, scabby, often oozing scars on the 

 surface of the fruit. Damage caused by plum curculio 

 is similar to that caused by the Lygocoris bugs. 



Research was done by Vanessa LeFebrve and 

 Roger Adams in Connecticut in 1981 and 1982 focus- 

 ing on methods to monitor these insects. Visual 

 traps were found to be more effective than sweep 

 nets or visual inspection. Like tarnished plant bugs, 

 the Lygocoris bugs appear to be "visual generalists" 

 and were attracted to several of the colors used in the 

 study. The most consistent results were achieved 

 using a peach blossom mimic, Pittsburgh Paint 

 "Pink Tiara." Traps placed high in the tree canopy 

 and with a vertical orientation, were highly effective 

 compared to traps placed low in the tree canopy, or 

 with a horizontal orientation. This result reflects 

 the fact that Lygocoris bugs fly in from the woods and 

 do not reside in the ground cover like tarnished plant 

 bugs. Traps placed in the woods bordering the 

 orchards also caught high numbers of these bugs. 

 Variability was high, but there appeared to be fairly 

 good correlation between trap captures, both in the 

 orchard and in the woods border, and fruit damage. 



Last summer we did a preliminary trial to see 

 whether any of the three species could be caught in 

 Massachusetts peach orchards. Rather than spend 

 time on further testing of traps, colors, and orienta- 

 tions, we used the combination that seemed most 

 successful in the Connecticut study: the "pink tiara"- 

 colored traps, hung vertically high in the canopy. 

 Traps were also hung in the woods around the 

 orchard, primarily on tree species known to harbor 

 Lygocoris. Four peach blocks were monitored, two of 

 which had very little crop due to the spring freeze. 

 We could not gather sufficient data to develop corre- 

 lations between trap captures and injury to peaches. 

 Generally, however, growers reported seeing cat- 

 facing very close to the time when bugs were cap- 

 tured. 



Traps in the orchards and in the woods caught 

 all three species of Lygocoris bugs, with L. omni- 

 vagus predominating slightly. There did not appear 

 to be a relationship between species captured and 



Fruit Notes, Winter, 1991 



