October and November are when Bronze Orange bugs (Stink bugs) appear on citrus trees in my area. The young ones are small and greenish, then they change to a bright orange and the adults look like large spiny cockroaches either brown or black. They cause damage to citrus trees by sucking sap.
The eggs of these sucking insects lay dormant over winter, emerging as tiny, green nymphs when it warms up. Towards the end of winter you should start checking the undersides of the leaves on your citrus trees, looking for egg clusters. It will be a simple matter to remove them at this stage before they hatch.
Oil sprays are effective at the nymph stage; perhaps spray every two weeks at the end of winter to reduce the number of adult bugs. You can pick the adults off by hand, but make sure you wear gloves and eye protection as they secrete a caustic, acrid substance.
Although they predominantly favour the citrus trees I am also seeing them on my tomatoes and eggplants.