Beneficials on farmland: identification and management guidelines (HGCA Summer 2008)
Bees, wasps and ants (Hymenoptera)
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Hymenoptera is a very large order with well over 6,500 species in Great Britain.
Usually have two pairs of wings - the front pair larger than rear. The wings are joined by a tiny set of hooks.
Hymenoptera can generally be split into:
- those without a waist - sawflies
- those with a waist - bees, wasps, ants, parasitic wasps.
Bees and wasps are divided into two main groups:
Adults feed on pollen and nectar and therefore require suitable flowers.
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Parasitica – nearly all parasites in which the ovipositor, the egg-laying organ, is adapted for piercing host tissue. Sometimes the ovipositor is two or three times as long as the body allowing the insect to reach hosts that may tunnel inside a plant. Parasitica include ichneumonidae, braconidae, chalcidae and proctotrupidae. Adult parasitoids are very sensitive to insecticides, so timing must be accurate.
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Ichneumonid wasp with moth caterpillar
© Tristan Bantock
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Gout fly parasitoid (Coelinus niger) and gout fly (left)
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Macroglenes penetrans, a parasite of orange wheat blossom midge, does not prevent crop damage, but can give long-term population control if 80% of midge larvae are parasitised.
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Ichneumonidae
- Ovipositor visible
- Long antennae
- Parasitic, mostly on other insects, particularly larvae of butterflies and moths (Lepidoptera)
- Often attack other parasites
Proctotrupidae
- Small or minute parasites
- Slender black insects
- Parasitise other insects, including eggs
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Braconidae
- Similar to Ichneumonidae
- One important group, eg Aphidius species parasitises aphids
- These cement host to plant before pupating
- Empty parasitised aphid skins, or mummies (usually golden), remain on plant
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Chalcidae
- Small insects, mostly under 3mm long
- Often brilliantly coloured with metallic greens or blues
- Have elbowed antennae
- Include pteromalids with triangular abdomen in profile
- Almost all parasites of pests or parasites of parasites
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Aculeata – social insects living in colonies. Social wasp, bee and ant colonies are headed by one or more queens which lay eggs. The workers, which are not fully-developed females, collect food, rear young, build the nest and rarely lay eggs. Male bees – drones – are much less common, appearing late in the year to mate with new queens.
Honey bee and ant colonies can last indefinitely with new queens replacing old ones from time to time.
Bumble bees and wasps start a new colony each year and only the mated queens survive overwinter.
In worker bees, wasps, and also some ants, the ovipositor has become a weapon and so only females can sting. Only the queens have an ovipositor.
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