Sawflies are a group of insect pests that can cause serious damage to trees, shrubs, and other plants. Proper identification, prevention, and control of sawflies are important for protecting plants.
What Are Sawflies?
Sawflies are not flies at all but are a type of wasp. The adult sawfly looks like a fly or bee but has two pairs of wings instead of one pair like flies. Sawfly larvae look like caterpillars and are often mistaken for them. There are thousands of different sawfly species.
Some common characteristics of sawfly larvae include:
- Segmented bodies with a head capsule
- Chewing mouthparts
- False legs along the abdomen
- No more than 8 pairs of prolegs
Unlike caterpillars, sawfly larvae have no crochets or hooks on the prolegs. The larvae feed on plant foliage, sometimes completely defoliating trees and shrubs.
Identifying Sawfly Species
Proper identification of sawfly species is important for effective control. Some ways to identify sawfly species include:
- Examine the larvae and their damage patterns on host plants
- Note the plant host – many sawflies are host specific
- Consider the time of year and geographic location
- Use a hand lens to look for distinguishing characteristics
- Consult an insect identification guide or local agricultural extension office
Some common sawfly species include:
- Pine sawfly – feed on pine trees
- Pear slug – feed on pear, cherry, plum, and cotoneaster
- Rose sawfly – feed on roses
- Elm leaf sawfly – feed on elm trees
Preventing Sawfly Infestations
There are several cultural practices that can help prevent or reduce sawfly infestations:
Select Resistant Varieties
Certain plant varieties are less susceptible to sawfly damage. Choose resistant trees, shrubs, and other plants whenever possible.
Proper Sanitation
Destroy any fallen leaves or plant debris where sawflies may be present. This removes potential overwintering sites.
Watering and Fertilization
Stressed plants are more vulnerable to sawfly damage. Maintain proper watering and fertilization practices to keep plants healthy.
Prune Affected Branches
Prune off branches with heavily infested foliage to reduce larval populations.
Use Row Covers
Floating row covers can exclude adult sawflies and prevent them from laying eggs on plants.
Rotate Crops
For vegetable crops susceptible to sawflies, practice crop rotation from year to year.
Controlling Existing Sawfly Infestations
If preventive measures have failed and sawflies are present, control methods include:
Hand Removal
It is possible to manually remove larvae from plants by picking them off or pruning infested branches. Drop them in soapy water to kill.
Insecticides
Insecticidal sprays and dusts can be applied against larvae. Always follow label directions carefully.
Biological Controls
Natural predators like birds can help control sawfly populations. Avoid use of broad-spectrum insecticides which also kill beneficial insects. Introduce parasitic wasps which will lay eggs inside sawfly larvae.
Traps
Adhesive traps can capture adult sawflies before they are able to lay eggs. Pheromone traps may attract certain species.
Conclusion
Sawflies can quickly defoliate and damage valued plants. Learn to identify different sawfly species in both the larval and adult forms. Employ preventive cultural practices in the garden and orchard to avoid infestations. For active sawfly populations, utilize manual removal, insecticides, biological controls, and trapping as needed. Pay close attention and take action at the first signs of sawfly damage before populations explode. An integrated pest management approach combining prevention and control is most effective against problematic sawfly pests.
Frequently Asked Questions About Sawfly Identification, Prevention, and Control
What are some key features to identify sawfly larvae?
Distinguishing features of sawfly larvae include segmented bodies with a distinct head capsule, chewing mouthparts, false legs along the abdomen, and no more than 8 pairs of prolegs without hooks or crochets.
How can I tell if sawflies are damaging my plants?
Look for ragged holes in leaves, detached leaves, branch dieback, and complete defoliation which may indicate sawfly larvae feeding. Distinguish them from caterpillars by lack of crochets on prolegs.
What plants do sawflies prefer to feed on?
Different sawfly species have different plant hosts including pine, rose, elm, pear, and cherry trees, as well as some herbaceous plants. Identifying the host plant can aid identification.
When should I take preventive measures against sawflies?
Take preventive cultural measures like sanitation, plant health, and physical barriers early in the season before sawflies are active and laying eggs. Monitor for early signs of damage.
How can I safely get rid of sawfly larvae manually?
Pick sawfly larvae off of foliage or prune infested branches. Drop larvae into soapy water, seal in a plastic bag, or freeze to kill before disposing. Always wear gloves when handling.
Are biological controls a stand-alone treatment for sawflies?
Natural predators and parasitic wasps will provide control but usually work best alongside limited insecticide use and cultural practices as part of an IPM program.