Sap beetles, also commonly called picnic beetles or picnic bug, are sometimes bothersome in gardens come late summer. They feed on overripe, damaged, and decomposing fruits and vegetables. There are nearly 200 species of sap beetles.
Adult sap beetles are between 1/8 and 1/4 inch long, black or dark colored and oval in shape. They have short wing covers and some varieties have small red or yellow spots on their wing covers. The antennae of sap beetles are knobbed at the ends.
Eggs of this beetle are small and milky white but are not generally noticed because they are laid within plant matter. The larvae are small , less than 1/10th of an inch, they are white , but some turn a pale yellow as they mature. The larvae a light brown head.
They overwinter as adults and reemerge in spring and lay eggs.
Eggs are laid near decaying plant material. When the larvae hatch, they feed for three to four weeks before pupating, they emerge as adults in mid summer.
Complete maturation, from egg to adult takes slightly over a month and there is one generation annually.
Control of Sap Beetles
Sap beetles can damage garden fruits and vegetables, but are more frequently found on damaged fruits and veggies that have been attacked by another insect, or are diseased. They are known to infest corn, melons, tomatoes, raspberries, strawberries, and fruits such as apples, pears and peaches that are wounded or overripe.
Removal of overripe fruits and vegetables is vital in combating this nuisance. Harvest tomatoes, melons, berries and other produce as soon as they ripen. Remove any damaged, diseased, or overripe fruits and vegetables at regular intervals. The collecting of ripe and decomposing fruits and vegetables is essential to eliminating the beetles food source and hence the beetles themselves.
Trapping Sap beetles {and some other garden pests} is one effective method of controlling their populations. Fermenting plant juices , placed a reasonable distance from working plants, but just outside your garden area will work well.
One mix that I found worked exceptionally well was a mixture of molasses water and fruit juice. Traps work best if placed a few feet from the garden. Remove the traps ‘victims’ 3 – 4 times weekly, and re-bait the traps.
Pesticides
Pesticides are not recommended for use against sap beetles, as they don’t appear until fruit is already ripened or over ripe. Any pesticides applied can kill existing beetles, but so long as ripe and decaying fruits are present, sap beetles will continue to heed the dinner bell and flock to your garden.
Should you decide to use pesticide, it is vital to observe an interval between insecticide application and harvest. Consult the pesticide label.
Early stages, the egg and larvae can be kept in check with Neem Oil and /or predatory insects such as Lady Bugs.
Most insecticides will also kill beneficial predators and parasites. Pyrethin