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Ministry of Agriculture, Food and Rural Affairs

braconid & Ichneumonid wasps

Braconidae and Ichneumonidae

Aphid mummy with braconid wasp larva removed Aphid mummy containing braconid wasp Aphid mummy with braconid wasp exit hole Braconid wasp Pholetesor ornigis adult (Credit the image to: Dr. RM Trimble, AAFC Vineland) Pholetesor ornigis cocoon with pupa (Credit the image to: Dr. RM Trimble, AAFC Vineland) Ichneumonid wasp parasitoid, with OBLR pupal case Macrocentrus ancylivorus, a braconid wasp, and its pupal case,  reared from oriental fruit moth Ichneumonid eggs on a caterpillar Ichneumonid larvae on same caterpillar
Click to enlarge.

Beginner

Scientific Names
Braconid wasps: commonly Pholetesor ornigis, Macrocentrus linearis (Nees) and Macrocentrus ancylivorus
Ichneumonid wasps: Gambrus and Itoplectis spp.

Identification
Braconid wasps

  • Often dark, though some are brightly coloured.
  • Range in size from 2-15 mm and have long antennae.
  • Appearance of braconid wasp immature life stages can be variable, though most or all development occurs within a host. 
  • Many braconid wasps leave the host as mature larvae and spin silken cocoons in which to pupate
  • A caterpillar surrounded by multiple small cocoons is an obvious sign of parasitism by braconid wasps. 
  • Other braconid wasps found in apple orchards specialize on aphids.
  • Parasitized aphid “mummies” are light brown and appear somewhat swollen, with a papery consistency.
  • An exit hole where the new wasp emerged may be present. 

Example:

  • P. ornigis  (braconid wasp) 
    Eggs: Laid directly into host leafminer larva. Not observed.
    Larva: Development occurs within the host, and larva leaves shrunken dead host to pupateLarva spins cocoon.  Not usually observed out of host.
    Pupae: The most identifiable lifestage of the parasitoid is the cocoon, which can be found within the mine and appears as a pale tightly woven tube-like structure with a dark band around the middle. A single new parasitoid is produced per mine. 
    Adult: Small black wasp not normally observed in the orchard. 

Ichneumonid wasps

  • Variable in size and colour (5-40 mm). 
  • Females will lay their eggs on or in the host, which may include both larval and pupal stages of caterpillars. 
  • As with braconid wasps, antennae are long. 
  • The abdomen is often longer than the thorax. 
  • Some species have very long ovipositors. 

Often Confused With
Parasitic wasps are often difficult to distinguishing between each other.  Learn to recognize the signs of parasitism in orchard pests.

Interaction with Host 
Braconid and ichneumonid wasps require a host for development.  Adult females will also feed on immature caterpillars. 

Braconid wasps attack a wide range of insect groups, including caterpillars, flies, beetles, and aphids, though many are specialized.  A common species in apple orchards is the native P. ornigis, a parasite that develops within its host. Larvae of leafminers, including the spotted tentiform leafminer, are among its hosts.  These wasps are effective biological controls of spotted tentiform leafminer in Ontario apple orchards.

Another species, M. linearis (Nees), attacks larvae of the obliquebanded leafroller. Other braconid wasps found in apple orchards specialize on aphids, and often several aphids within a colony may be parasitized.  

Period of Activity
Tight cluster through harvest.

Monitoring and Management
Look for aphid mummies when monitoring aphid populations. Check for the presence and abundance of braconid wasp cocoons while monitoring for spotted tentiform leafminers. The lifecycle of the tentiform leafminer and P. ornigis are synchronized, with adults emerging in spring just as the first sap feeders appear, typically around petal fall. These parasitoids are sensitive to many broad-spectrum insecticides. Select reduced-risk products when spraying for other pests where options exist. 

Advanced

Scientific Names
Three braconid wasp species commonly found in apple orchards include Pholetesor ornigis, Macrocentrus linearis (Nees) and Macrocentrus ancylivorus.  Ichneumonid wasps include Gambrus and Itoplectis spp.

Identification
Braconid wasps
Braconid wasps are often dark, though some are brightly coloured. They range in size from 2-15 mm and have long antennae. Their wings contain very few veins and have a window-like appearance, and their abdomens are rarely longer than the thorax.  Adults are not usually observed in the orchard. 

Braconid wasp immature life stages (larvae and pupae) vary in their appearance.  Some species, such as those parasitizing aphids, develop from egg to pupa entirely within the body of the host, with emergence only as an adult.  Other species leave the host as mature larvae and spin silken cocoons in which to pupate

Some braconid wasps produce a single parasitoid per host.  However, many species, including some Macrocentrus spp., will lay a single egg, which then divides inside the host to produce several wasp larvae.  A caterpillar surrounded by multiple small cocoons is an obvious sign of parasitism by a braconid wasp. 

Other braconid wasps found in apple orchards specialize on aphids; parasitized aphid “mummies” are light brown and appear somewhat swollen, with a papery consistency.  An exit hole where the new wasp emerged may be present. 

Examples of braconid wasps include the following:

  • P. ornigis  (braconid wasp) 
    Eggs: Laid directly into host leafminer larva.  Not observed.
    Larvae: Development occurs within the host, and larva leaves shrunken dead host to pupateLarva spins cocoon.  Not usually observed out of host.
    Pupae: The most identifiable lifestage of the parasitoid is the cocoon, which can be found within the mine and appears as a pale tightly woven tube-like structure with a dark band around the middle. A single new parasitoid is produced per mine. 
    Adult: Small black wasp not normally observed in the orchard. 
  • Macrocentrus ancylivorus
    Eggs: Laid directly into host oriental fruit moth larva.  Not observed.
    Larvae: The first three instars feed inside the caterpillar host, while the fourth feeds externally.  The final instar larva (4-5 mm) spins a cocoon
    Pupae: The most identifiable lifestage of the parasitoid is the cocoon containing a brown oblong pupa (4 mm).   
    Adult: Main body of the adult is 5 mm, with equally long ovipositor and antennae. Slender insect with brown-red appearance. 

Ichneumonid wasps
Ichneumonid wasps are variable in size and colour (5-40 mm).  Females will lay their eggs on or in the host, which may include both larval and pupal stages of caterpillars.  As with braconid wasps, antennae are long.  The abdomen is often longer than the thorax.  Some species have very long ovipositors. 

Often Confused With
Parasitic wasps are often difficult to distinguish between each other.  Learn to recognize the signs of parasitism in orchard pests.

Interaction With Host 
Braconid and ichneumonid wasps require a host for development.  Adult females will also feed on immature caterpillars. 

Braconid wasps attack a wide range of insect groups, including caterpillars, flies, beetles, and aphids, though many are specialized.  A common species in apple orchards is the native P. ornigis, a parasite that develops within its host. Larvae of leafminers, including the spotted tentiform leafminer, are among its hosts. P. ornigis overwinters as a prepupa within a cocoon in the leaf mine of the host. Females emerge in the spring and deposit eggs individually into leafminer larvae. Parasitized larvae remain active until they reach the final instar or pupal stage, after which they are killed by the developing wasp larvae. The wasp larva exits the leafminer larva and pupates within a cocoon. The wasp biology is well-synchronized with the host species. There are several generations per year. These wasps are effective biological controls of spotted tentiform leafminer in Ontario apple orchards.

Another species, M. linearis (Nees), attacks larvae of the obliquebanded leafroller (OBLR).  Research conducted in commercial apple orchards in Michigan showed braconid wasps (Bassus dimidiator Nees and M. linearis) accounted for approximately 50% of the parasitism observed in OBLR. 

Other braconid wasps found in apple orchards specialize on aphids, and often several aphids within a colony may be parasitized.  

Period of Activity
Many species are synchronized with their host biology. 

Monitoring and Management
Look for aphid mummies when monitoring aphid populations. Check for the presence and abundance of braconid wasp cocoons while monitoring for spotted tentiform leafminers. The lifecycle of the tentiform leafminer and P. ornigis are synchronized, with adults emerging in spring just as the first sap feeders appear, typically around petal fall. These parasitoids are sensitive to many broad-spectrum insecticides. Select reduced-risk products when spraying for other pests where options exist.