Southeastern Apple Production
ENTOMOLOGY
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Southeastern Apple ProductionENTOMOLOGY |
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An adult San Jose scale (SJS) female is about 1/10 inch in diameter, round, and white to gray with a raised spot in the center. Males are slightly smaller, more elongated, and have a raised spot on the larger end. Active immature scales (crawlers) are 1/100 inch long and bright yellow. Though the wingless females never emerge from the scales, the winged males do emerge to fertilize the females in spring.
 Adult detail |
 Infested apples |
 Adult male |
SJS overwinter on twigs as nymphs under waxy scale coverings. Adult males emerge and fertilize females around late April, mating directly through the females' waxy coverings. Females give live birth to approximately 400 young in mid-May, and nymphs crawl around the plant searching for a place to insert their long mouthparts. If a female, the nymph will shed her skin, lose her legs and antennae, and become a flattened sack attached to the twig or fruit. She will secrete a waxy covering that hardens into the protective scale where she spends the rest of her life. Males also lose legs and antennae after attaching to the plant, but will eventually redevelop these parts to emerge and seek out females.
If left unchecked, SJS has the potential to kill trees by sucking out nutrients. The entire surface of the bark may be covered with overlapping scales, and fruit will exhibit reddish rings where scales attach. Heavily infested trees will suffer from diminished vigor and thinner foliage.
 Scales on trunk |
 Scales on twig |
 Red rings around scales |
Populations can be monitored by either checking adult male emergence or crawler emergence. For adult males, pheromone traps should be placed in trees with known active populations (if any) at the pink stage. Crawlers can be monitored by wrapping black electrical tape that has been coated with petroleum jelly around infested branches. First sprays can be timed as adults are caught in the traps or crawlers caught on the tape.
Insect and Mite Management Overview
Insect and Mite Index
Southeastern Apple Production
Mountain
Horticultural Crops Research & Extension
Center
455 Research Drive
Mills River, NC 28759
Phone: 828.684.3562 ~ Fax: 828.684.8715
Email: jim_walgenbach@ncsu.edu
Web Crafters: Anne S. Napier and
Steve Schoof
Email:
steve_schoof@ncsu.edu
Updated March 12, 2007