|  As their name implies, post oak grasshoppers prefer post oak (Quercus stellata), but they can also be found on water oak (Q. nigra), blackjack oak (Q. marilandica) and bluejack oak (Q. incana). It is not uncommon to find them feeding on a range of other trees, including hickories (Carya spp.), white ash (Fraxinus americana), flowering dogwood (Cornus florida), red maple (Acer rubrum) and sweetgum (Liquidamber styraciflua) (Hilliard and Himes 2005). However, they tend to feed more on these non-oak trees following severe defoliation of their preferred oak trees. In general, tree feeding among grasshoppers is very rare, and the large majority of the closest relatives to post oak grasshoppers tend to be generalist feeders that eat a mixture of grasses and broad leaf plants. Taxonomic information on the post oak grasshopper can be found at the Orthoptera Species File Online.
Adult females lay their eggs in the ground, and we have found that individuals typically produce 5-6 eggs at a time (although in Wisconsin single females have been reported producing as many as 12 eggs at a time). These eggs are contained within a pod, surrounded by a protective foam, and remain in the ground through the summer, fall and winter. In late March/early April, the eggs begin to hatch, shortly after the oak trees bud and produce new leaves. The hatchlings are great  climbers, and seem to prefer to eat young, soft leaves. Immatures proceed through 5 developmental stages, called instars, before molting into adults. The first three instars are very cryptic on oak trees, and blend easily with the bark of the tree (the picture above is a 3rd instar, which on average is about 10-12 mm long). As they enter the 4th and 5th instars, they undergo a slight color change, becoming more yellow. The picture to the left is of a 4th instar, which grow to about 15-18 mm. The adults (top picture) look very different from the immatures, and the large majority (>95%) are characterized by having short wings and are flighless. The rest of the population has either long- or intermediate-length wings, although neither of these forms is capable of flight. The adults begin to appear in late April/early May, and remain alive until early/mid June. A significant proportion of the population can be infected with a pathogenic fungus, and this can be a major cause of mortality. Infected individuals that have died often burst when touched or disturbed and release fungal spores. In Wisconsin, vertebrate and invertebrate predators have been observed (Valek and Coppel 1972), and in Texas chickens are known to readily eat post oak grasshoppers (Terry Junek, personal observation). | |
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increasing body size) in late April. You can click on the picture to the right to see a larger view of immature post oak grasshoppers aggregating. Individual pictures of immature post oak grasshoppers can be seen below, in the biology section.
