Peach Pests I: 



Insects That Feed on Peach Fruit 



Karen I. Hauschild 



University of Massachusetts Cooperative Extension System 



In Massachusetts there are several insect 

 species that feed on developing peaches. Two 

 types of damage result from this feeding: surface 

 scarring and the resulting malformation (com- 

 monly referred to as "catfacing") and larval 

 tunneling into fruit flesh. Injured fruit either 

 drop prematurely or are downgraded in the 

 sorting process. 



Fruit scarring is caused by two groups of 

 insects in the order Hemiptera, the "true bugs." 

 The tarnished plant bug and a complex of true 

 bugs known as the oak-hickory plant bugs feed 

 on young, developing peaches with resulting 

 damage appearing as dimpling or surface scar- 

 ring. Several species of stink bugs cause similar 

 damage. Most serious damage occurs between 

 petal fall and when fruits are 1/2 to 3/4 of an inch 

 in diameter. 



The oriental fruit moth, plum curculio, and 

 walnut husk fly lay eggs in developing fruit. If 

 these eggs hatch, larvae then tunnel in fruit 

 flesh, a type of damage that results in fruit drop 

 or non-marketability. 



Below is a brief description of the biology of 

 each of these pests, the damage each causes, and 

 basic information on non-chemical control. 



Catfacing Insects 



Tarnished Plant Bug. The tarnished 

 plant bug (Lygus lineolaris) is a small, 1/4-inch 

 long, golden to brown bug with white and yellow 

 markings. Adult tarnished plant bugs overwin- 

 ter in hedgerows, in leaf litter, under tree bark, 

 and in other protected areas in and around 

 orchards. Plant bugs emerge early in spring, 

 and feed on buds as they begin to swell. If 

 damage is severe, developing fruit buds will dry 

 up and drop off. If damage occurs to blossoms or 

 young fruit, catfacing, scarring, or dimpling will 



result. 



Tarnished plant bug damage usually is most 

 serious following mild winters, in areas bor- 

 dered by woodlands or fields, and in orchards 

 next to fields of alfalfa or ones with a high 

 population of alfalfa plants in the ground cover. 



White, rectangular sticky traps hung low in 

 peach trees can be used to monitor tarnished 

 plant bugs in peach orchards. At the present 

 time there is no economic threshold level, but 

 presence/absence can be used to indicate the 

 need for chemical control. 



Oak-hickory Plant Bugs. Three species of 

 the genus Lygocoris - L. caryae, the hickory 

 plant bug; L. quercalbae, the white oak plant 

 bug; and L. omnivagous — are commonly re- 

 ferred to as the oak-hickory plant bugs. All 

 appear similar to the tarnished plant bug - 

 brown to yellowish-brown in color, but without 

 the tarnished appearance. These insects over- 

 winter as eggs on oak, hickory, and other tree 

 species. Adults migrate to peach in early June, 

 a few weeks after shuck split, with peak num- 

 bers appearing in mid-June. Adults apparently 

 do not live in peach trees, but seem to pass 

 through in an unpredictable pattern. Oak- 

 hickory plant bug damage results in catfacing - 

 sunken, scabby, oozing scars. 



Rectangular pink (Pittsburgh "Pink Tiara") 

 traps placed high in the peach tree canopy can be 

 used to monitor presence and numbers. No 

 economic threshold level has been established. 



Stink bugs. Several species of stink bugs 

 cause catfacing injury to peaches. Acrosternum 

 hilare, the green stink bug; Euschistus spp., the 

 brown stink bug; and Thynata spp. all have been 

 found in peach orchards. These insects are 

 shield-shaped, flattened, with narrow heads 

 and short legs. When disturbed, they emit a 



14 



Fruit Notes, Spring, 1992 



