Stink bugs are found occasionally in almonds. They feed on the almond hulls from late April through July, causing gummosis and kernel abortion. Typically, multiple feeding points are found on an almond and within an area of the tree, with few feeding holes extending into the kernel after shell hardening. Even without reaching the developing kernel, excessive feeding can still cause crop loss, kernel discoloration, as well as infections of the fruit by yeast, other fungi, and bacteria.
There are several different species of stink bugs that affect almonds. Most common is the green stink bug, but the red-shouldered stink bug can also be found. These insects tend to move into the field during the spring when weed or crop hosts begin to dry up – which tends to be earlier in years of low winter rains. The green stink bug may also overwinter within the orchard. Eggs tend to be barrel-shaped and laid in clusters on hulls.
There are currently no treatment thresholds for stink bugs. The decision to treat should be based on the appearance of damage and the extent of the damage. Monitor the orchard for gummosis and try to observe the pest to separate it from feeding that may be caused by leaf footed plant bug. Unlike leaf-footed plant bug, stink bugs aren’t as mobile and sprays can be very effective. Use of a broad spectrum insecticide should reduce populations. Data suggests that an application typically reduces populations enough that another treatment may not be needed for three years.
More information can be found at the UC IPM Webpage for Stink Bugs.
Pete Goodell
May 4, 2015Dave:
Your readers might also be interested in this PDF publication, Field Guide to Stink Bugs, from Virginia Cooperative Extension. It covers many of the local stink bugs as well as a national perspective.
It is available as a download here
https://pubs.ext.vt.edu/444/444-356/444-356.html
David Doll
May 4, 2015Thanks Pete! I agree, that is a great guide!