Insect of the Month - Non-pest Pests - Wasps/Yellow jackets/Hornets and Hawthorn Lace Bugs

  Hort Snacks - August 2018
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 A number of insects that are considered nuisance or “minor” pests in certain situations or may become problematic of some crops

Crops Affected:
Wasps / Yellowjackets / Hornets (Vespula spp., Dolichovespula spp., Vespa spp.); – strawberries, raspberries & other fruit crops

Life Cycle:

  • Not pests but are scavengers
  • Queens build a nest in a range of sheltered areas, such as buildings, woodpiles, underground or unprotected areas like trees and shrubs
  • Populations increase over the summer, peaking in fall
  • Workers scavenge for insects or rotting fruit
  • Mating occurs in the fall and fertilized queens overwinter
  • Don’t damage crops, but feed on damaged or over-ripe fruit
  • May be present during harvest
  • Nests may be difficult to locate
  • Large numbers of visible wasps may indicate the presence of a nest
  • Warm, dry springs can produce larger wasp problems in August than cool, wet springs
  • Regular sanitation can help keep populations lower; this would include prompt harvesting of all ripe berries and clean picking practices
  • It has been suggested that the presence of another nest will deter settlement of an area, therefore false nests may be effective deterrents
  • Careful destruction or removal of existing nests
Wasp Adult
Photos by Robert Spencer

Hawthorn Lace bug (Corythucha cydoniae) – Saskatoon berry and other plants in the Rose family (apples, hawthorn, pear, cotoneaster, etc.); other species may affect Saskatoon, chokecherry, etc.

Life Cycle:
  • Overwinter as adults (Two generations per season)
  • Black eggs are laid in clusters on the underside of leaves in early spring
  • Nymphs emerge and feed on the underside of the leaves after about 3 weeks
    • 5 instars; 1st generation of adults emerge in midsummer, 2nd in fall
  • Feed by piercing leaves and sucking out plant juices
  • Stippled or mottled leaves with many lace bugs present
  • Feed in large numbers
    • leaves may be stained with their excrement
  • Adults are small bugs which appear to be covered in lace
  • Nymphs are dark brown to black and covered in varying amounts of spines
  • Not required, but can be detected while scouting for other insect pests
  • Not typically required, as do not typically cause economic damage
  • May be controlled during chemical applications for other registered pests
Hawthorn lace bug nymph
Hawthorn lace bug adults
Severe leaf stippling and discolouration
Lace bug injury on Saskatoon berry – yellowing / stippling
Evidence of lace bugs on leaf undersides – nymphs, adults, frass and stippling of leaves
Photos by Robert Spencer
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on July 30, 2018.