Treehoppers

Membracidae. Spanish: Saltones torritos, saltarines (General).

Most treehoppers are small (BL 2-12 mm). If they were much bigger, they would be the hobgoblins of the insect world because they exhibit a tremendous variety of bizarre body forms, all the result of modifications of the shape of the dorsal shield of the prothorax. The function of this structural elaboration has been much debated. Evidence indicates that a variety of purposes are served (Boulard 1973), including cryptic mimicry (especially the thorn-shaped types), sexual display, apose-matic coloration, and self-amputation (apo-physectomy; the structure is loosely attached and easily detaches when jostled) (Mann 1912). The presence of numerous sensory hairs on its surface suggests a role in perception of odor, air currents, or sound (Wood and Morris 1974), but this is not likely a definitive purpose since such sense organs are widely placed and not specialized in structure or distribution.

These homopterans are otherwise basically similar to leafhoppers, except their wings are partly concealed by the enlarged prothorax and they have stouter legs. Also there are only two ocelli, and the bristlelike antennae arise anterior to the eyes.

The nymphs are commonly very spiny, especially along the middle of the back. They often form aggregations after hatching in company with their maternal parent. In many species, the latter practices brood care, hovering over her eggs and living among the nymphs until they mature (Wood 1979, Hinton 1977). Aggregations are sometimes composed of mixed species.

The majority of treehoppers are actually solitary, but presocial behavior has developed in some subfamilies, possibly out of mutualism with ants in lowland, wet tropical forests (Wood 1984). Nymphs secrete copious honeydew, which attracts ants and other insects seeking this nutritious substance. Treehoppers thus provide sustenance for aggressive ant species that guard them from insectivores (Wood 1984). In Brazil, Aetalion reticulatum (a species in the related family Aetalionidae) is served by two protectors alternately: stingless bees deter enemies during the day and are replaced by Camponotus ants at night (Castro 1975).

The family is well represented in Latin America. There are about 190 genera containing approximately 1,250 species

(Deitz 1975; Metcalf and Wade 1963, 1965; Funkhouser 1927). A correlation seems to exist between a low number of species per genus in lowland regions and lessened host specialization (Wood and Olmstead 1984).

Because of their strange shapes, variety, and colors, treehoppers have attracted the attention of many entomologists and artists who have portrayed them elegantly (Buckton 1903, Fowler 1894-1909). They exhibit an infinite variety of structure, some of which tends to sort into a few generalized types, depending on the basic form of the pronotum. Some of these are the single thorn shape (Umbonia; fig. 8.10a); double thorn shape (Hemikyptha); compressed wedge types (Membracis; fig. 8.10f); carriers of clusters of four spherical swellings on stalks (Cyphonia, Bocydium [fig. 8.10c], Eucyphonia)\ bulbous form (Combophora; fig. 8.10d); ball-with-handle form, or very long with a bulbous swelling posteriorly (Heteronotus; fig. 8.10b); crested, or branching spongiform excrescences (Spongophorus; fig. 8.10e); and fusiform (Polyglypta) types. Treehoppers are not notable wax producers, although the egg masses of some species are sometimes covered in waxy secretions.

Membracids are seldom injurious. Met-calfiella monogramma (periquito del aguacate) sometimes damages avocados in Mexico (Camacho 1944). Biological information

figure 8.10 TREEHOPPERS (MEMBRACIDAE). (a) Thorn mimic (Umbonia spinosa). (b) Spine mimic (Heteronotus flavomaculatus). (c) Small treehopper (Bocydium sp.). (d) Inflated treehopper (Combophora sp.). (e) Fungiform treehopper (Spongophorus sp.). (f) Crested treehopper (Membracis on the family generally is scant. The life history strategies of some Neotropical species have been described (Wood 1984).

References

Boulard, M. 1973. Le pronotum des Membra-cides: Camouflage sélectionné ou orthoge-nése hypertélique? Mus. Nat. Hist. Natur. (Paris) Bull. (ser. 3) 83: 145-165.

Buckton, G. B. 1903. A monograph of the Membracidae. Lovell Reeve, London.

Camacho, A. D. 1944. El periquito del aguacate. Fitófilo (México) 3(4): 3-54.

Castro P. R. C. 1975. Mutualismo entre Trígona spinipes (Fabricius, 1793) e Aethalion reticu-laturn (L. 1767) em Cajanus indiens Spreng. na presença de Camponotus supp. Cien. Cult. 27(5): 537-539.

Deitz, L. L. 1975. Classification of the higher categories of the New World treehoppers (Homoptera: Membracidae). N.C. Agrie. Ex-per. Sta. Tech. Bull. 225: 1-177.

Fowler, W. W. 1894-1909. Rhyncota: Hemip-tera-Homoptera. Biología Centr. Amer. Vol. 2, pt. 1.

Funkhouser, W. D. i927. Membracidae, general catalogue of the Hemiptera. Smith College, Northampton, Mass., Fase. 1.

Hinton, H. E. 1977. Subsocial behavior and biology of some Mexican membracid bugs. Ecol. Entomol. 2: 61-79.

Mann, W. M. 1912. A protective adaptation on a Brazilian membracid. Psyche 19: 145-147.

Metcale, Z. P., and V. Wade. 1963. A bibliography of the Membracoidea and fossil Homoptera (Homoptera: Auchenorhyncha) [sic]. N.C. State Univ., Raleigh.

Metcalf, Z. P., and V. Wade. 1965. General catalogue of the Homoptera: A supplement of Fascicle 1: Membracidae of the General catalogue of Hemiptera. Membracoidea. Sec. 1 — 11. N.C. State Univ., Raleigh.

Wood, T. K. 1979. Sociality in the Membracidae (Homoptera). Entomol. Soc. Amer. Misc. Publ. 11: 15-22.

Wood, T. K. 1984. Life history patterns of tropical membracids (Homoptera: Membracidae). Sociobiology 8: 299-344.

Wood, T. K, and G. K. Morris. 1974. Studies on the function of the membracid pronotum (Homoptera). I. Occurrence and distribution of articulated hairs. Can. Entomol. 106: 143-148.

Wood, T. K., and K. L. Olmstead. 1984. Latitudinal effects on treehopper species richness (Homoptera: Membracidae). Ecol. Entomol. 9: 109-115.

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