2010, M[ark] S[tanislaw] Goettel, J[ørgen] Eilenberg, T[ravis] Glare, “Entomopathogenic Fungi and Their Role in Regulation of Insect Populations”, in Lawrence I[rwin] Gilbert, Sarjeet S[ingh] Gill, editors, Insect Control: Biological and Synthetic Agents, London; Burlington, Mass.: Academic Press, →ISBN, page 405:
Some fungus mediated behavioral changes have been recorded, such as "summit disease" where infected grasshoppers climb to the top of plants to die[…]. This may aid spore dispersal, but it has also been suggested that it is a mechanism by which the host reduces infection through increased exposure to UV.
2012, David I[an] Shapiro-Ilan, Denny J[oseph] Bruck, Lawrence A[nthony] Lacey, “Principles of Epizootiology and Microbial Control”, in Fernando E. Vega, Harry K[azuyoshi] Kaya, editors, Insect Pathology, 2nd edition, London; Waltham, Mass.: Academic Press, →ISBN, figure 3.2 caption, page 38, column 2:
Soybean looper, Thysanoplusia orichalcea, infected with Thysanoplusia orichalcea nucleopolyhedrovirus. The image illustrates what is known as treetop disease or summit disease, whereby the host climbs to an exposed position (e.g., on vegetation) before death to facilitate dispersal of the pathogen.
2014, D[enny] J[oseph] Bruck, “Entomopathogens as Insect Biocontrol Agents”, in Robert G[rant] Linderman, D[avid] Michael Benson, editors, Compendium of Rhododendron and Azalea Diseases and Pests, 2nd edition, St. Paul, Minn.: APS Press, →ISBN, page 84, column 2:
Many foliar-feeding hosts infected with bacterial and viral pathogens display classic "summit" diseases, in which the infected insects move up the foliage immediately before they die. This behavioral host response to infection results in increased transmission to uninfected hosts, as the pathogen propagules from the cadaver shower down on the foliage below, resulting in increased transmission to the rest of the population.
A particularly striking example of host manipulation called ‘summit disease’ occurs across a wide range of insect groups including aphids, grasshoppers, butterflies and moths, beetles and ants. The fungus grows within the host’s body, infecting various organs, but before it reaches a point when the animal can no longer move, somehow the fungus causes the host to climb to a higher point like the top of a grass stem or tree and wait there to die. This can be beneficial to the fungus as from this elevated position they can spread their spores far and wide on the breeze.
In the case of Ophiocordyceps, an infected ant's behaviour can be thought of as fungal behaviour. The death grip, summit disease, these are extended characteristics of the fungus, part of its extended phenotype.
Entomophaga grylli on Wikipedia.Wikipedia 