damage they cause or by seeing their movement 

 on leaf surfaces. Female mites overwinter in the 

 orchard understory or under tree bark. Eggs laid 

 in early May hatch in 5 to 8 days. Larvae (young 

 mites) are pale to dark green with two dark 

 spots. One generation can be completed in as few 

 as 21 days, resulting in up to nine generations 

 per growing season. Mite damage appears as 

 leaf stippling or off-color foliage. 



Under optimal conditions predator mites 

 can control two-spotted mites; however, these 

 predators are killed by non-selective pesticides 

 such as the synthetic pyrethroids. Mite levels 

 should be monitored, especially in trees which 

 have had infestations in past years. Hot, dry 

 weather favors mite build-up. Check with your 

 local county agent or fruit specialist for updated 

 information on mite treatment threshold levels. 

 One predator mite for every 5 to 7 pest mites 

 usually results in biological control. 



Oriental Fruit Moth 



As mentioned in "Peach Pest I," first genera- 

 tion larvae of the Oriental fruit moth burrow 

 into rapidly growing peach terminals. Larvae 

 enter near a leaf axil and tunnel down the shoot 

 core for up to six inches, killing the affected 

 terminal. As terminal growth hardens, larvae 

 move to peach fruit as a food source. (Refer to 

 "Peach Pests I" for additional information on 

 Oriental fruit moth.) 



Peach Tree Borer 



The peach tree borer (Synanthedon exitosa) 

 and the lesser peach tree borer (Synanthedon 

 pictipes) are the most serious pest of peach wood. 

 Larval tunneling by both species weakens trees 

 and serves as entry sites for canker diseases. 



Adult peach tree borers are clearwing 

 moths. Females are dark blue with a broad 

 orange band encircling their abdomens. Their 

 front wings are blue, while their hindwings are 

 clear. Adult males are lighter blue with several 

 yellow stripes around their abdomens and with 

 both pairs of wings clear. Larvae are cream to 

 light yellow with brown heads and are 1 to 1.25 

 inches long when fully grown. Larvae have three 



pairs of true legs and four pairs of fleshy "pro- 

 legs." 



Peach tree boers overwinter as larvae within 

 their burrows. Warm weather (temperatures 

 greater than 50°F) prompts larvae to begin 

 feeding in the spring. Larvae leave their bur- 

 rows to construct their pupal cocoons. These 

 pupae complete their transformation in about 

 four weeks. Cocoons can be found in an upright 

 position just beneath the soil near the tree 

 trunk. In our area, adults emerge from early 

 July into September. Adults mate soon after 

 emerging and egg-laying begins almost immedi- 

 ately after mating. Each female lays an average 

 of 400 reddish-brown eggs under loose bark, 

 near wounds, in cracks, or on other rough areas 

 on tree trunks. These eggs hatch in about 10 

 days, and the larvae immediately tunnel into 

 the bark on the lower tree trunk, feeding on the 

 cambium layer. These larvae then remain in the 

 tree until the following spring. 



Adult male emergence and peak activity can 

 be monitored with pheromone traps. Signs of 

 larval activity include sap exuding from tree 

 trunks or build-up of frass (insect excrement and 

 wood particles) at the base of the tree. Non- 

 chemical controls that have been recommended 

 in the past included using a stiff wire to kill 

 larvae in their tunnels and mounding moth balls 

 at the base of trees. These measures, however, 

 are often not practical in a commercial peach 

 orchard. Mating disruption, baiting an orchard 

 with synthetic pheromone, may soon be avail- 

 able as a practical alternative to chemical con- 

 trol. 



Lesser Peach Tree Borer 



Adult lesser peach tree borers are very simi- 

 lar in appearance to male peach tree borer 

 adults. They, too, are blue-black clear-winged 

 moths with yellow bands on their abdomens. 

 Larvae are light tan to cream-colored with dark 

 heads and are about one inch long when mature. 



Lesser peach tree borers overwinter as lar- 

 vae in galleries beneath bark. Larval develop- 

 ment is completed in the spring after which the 

 larvae burrow into the outer bark surface to 

 pupate. Adult emergence begins in late May and 



Fruit Notes, Summer, 1992 



13 



