The tiny Asian citrus psylid is killing citrus trees in California (High res image from UC Davis here).
Homegrown Evolution has an interesting story about Asian citrus psylid, and ant-sized insect that could spell doom for California citrus.
The Asian citrus psylid is not a problem in itself, but carries an incurable bacterial disease called huanglongbing (HLB). HLB, first reported in Asia in 1919, renders citrus fruit inedible and eventually kills the tree. Parts of Africa, Asia and South America are infected with HLB and in some regions of Brazil the disease is so bad that they've given up growing citrus altogether. HLB is in Florida and is adding to a nightmarish collection of other diseases afflicting citrus in the Sunshine State. Now California growers are panicking with the appearance of the psylid.
The State of California is taking all sorts of measures to stop the spread of the pest (including spraying dangerous pesticides), but Erik and Kelly of Homegrown Evolution are taking a Stoic approach to the problem.
Seneca [author of Letters from a Stoic] would say, do what is in your power to do and don't worry about what you can't fix. Taleb [author of The Black Swan] would advise always maximizing upside potential while minimizing exposure to the downside. My unsentimental conclusion: don't try to grow citrus. If I had a mature tree I'd leave it in place and rip it out at the first sign of HLB. Despite the state's offer to replace any HLB infected tree with a free citrus tree I wouldn't take them up on the offer. In our case we have three small, immature citrus trees that are already chewed up by citrus leafminers. I'm pondering pulling them up and replacing them with fruit trees unrelated to citrus. This follows our stoic, get tough policy in the garden. Planting a tree entails a considerable investment in time. It can take years to get fruit. Why not plant pomegranate instead and let other people worry about citrus diseases? If a pomegranate disease shows up, rip it up and plant something else. Following this approach will eliminate habitat for the psylid and negate the need for pesticides.