Genus Timema

Timema Scudder 1895

21 spp., of which 20 are in our area(1) (There are at least two more undescribed taxa, one on Pinus flexilis and one on Hesperocyparis sargentii)

♂ 11‒20 mm; ♀ 14‒28 mm

revised in (2) (more taxa described subsequently)

dependable species ID requires study of the terminalia, especially of the male • helpful views of terminalia: dorsal for males; dorsal, ventral, and lateral for females

Males have asymmetric terminalia with two variously lobed cerci ("claspers"), and a more-or-less ribbon-like projection between them (positioned next to the right cercus and called the "intradextral process"). Figures appear here. Keys refer to left and right cerci using the latin terms "sinistral" and "dextral", respectively.

Female terminalia are symmetric • terminalia of all described species shown at

In bisexual species, adults (as opposed to immature instars or "nymphs") are usually seen paired rather than alone...due to the prevalence of "mate guarding" behavior, in which adult males ride on the backs of adult (or near adult) females for long periods (from hours up to several days). Males are noticeably smaller than females in body size. A rule of thumb given in Sandoval & Vickery (1996) is that a field observation of 5 or more adult females with no males present is a likely indicator of an asexual species.

To each asexual species there corresponds a sexual species whose females are visually indistinguishable:

sw.US and Baja • the map below provides approximate ranges, e.g. of the following species:

On foliage, twigs, branches or near base of host plants. Sometimes under stones. Host plants mostly associated with chaparral; some with woodlands or forest (e.g. douglas fir, redwood). Green morphs tend to rest on leaves; brown/gray morphs on branches or ground. Unstriped morphs are usually associated with broadleaves (e.g. oaks, ceanothus, manzanita, etc.); striped ones, with plants having needle-like leaves (e.g. chamise, douglas fir, redwood, etc.)

known hosts:

In most species, eggs are dropped from branches of host plants. T. douglasi, T. genevievae, T. monikense, T. shepardi, and T. tahoe are parthenogenetic (anomalous males occur in T. monikenesis and T. shepardi). Most of these have a more northerly distribution than their corresponding sexual species; some (e.g. T. genevievae) have been asexually reproducing for over a million years.

during egg-laying, females defecate previously ingested soil, then use their cerci to cover/pack the eggs with soil (this may prevent desiccation, reduce parasitism, and protect from fires common in chaparral habitats); soil is found in the gut of newly hatched larvae and Sandoval has observed that laboratory-hatched eggs of all species survived only when provided with soil from their native locality in the first few days after hatching. It is thought that the soil provides offspring access to microbial symbionts for digestion of host plant foliage. Tachinid flies parasitize larvae of several spp.

Timema is the only member of suborder Timematodea, basal to the rest of Phasmida (cladogram)

T. genevievae was the first Timema recognized as parthenogenetic. Rentz noted that while other species known at the time emitted an acrid odor, T. genevievae did not. Weissman suggested that the odor may be associated with mating-related pheromones lost in asexual species.(2)

D. Arbuthnott, M. G. Elliot, M. A. McPeek, & B. J. Crespi (2010). Divergent patterns of diversification in courtship and genitalic characters of Timema walking-sticks. J. Evolution Biol. 23(7) 1399:1411 (PDF)

Bartman, G. & Brock, P. D. (1995). Observations of the appearance and behavior of species of the stick-insect genus Timema Scudder (Phasmida: Timematodea). Bulletin of the Amateur Entomologist's Society, 54:197-203 (Full Text & photos)

Burrows, Malcolm (2008). Jumping in a wingless stick insect, Timema chumash (Phasmatodea, Timematodea, Timematidae). Jour. Experimental Biol. 211: 1021-1028 (Full Text)

Hebard, M. (1920) The genus Timema Scudder, with the description of a new species, (Orthoptera, Phasmidae, Timeminae). Entomological News, 31 126-132 (Read at BHL)

Hebard, M. (1937) Studies in Orthoptera [...]:Notes and a new species of Timema [...]. T. Amer. Entomol. Soc, 63 (3), pp. 347-350. (Read online)

Law, J. H. & B. J. Crespi (2002). The evolution of geographic parthenogenesis in Timema walking-sticks. Molecular Ecology 11: 1471–1489 (PDF)

Maderspacher, Florian (2011). Asexuality: The Insects that Stick With It. Current Biology, 21 (13) pp. 495-497 (Read online here)

Rentz, D. C. F. (1978). A new parthenogenetic Timema from California. Pan-Pacific Entomologist, 54 (3): 173-177. (Full Text)

Sandoval, C.P. (1994). Differential visual predation on morphs of Timema cristinae (Phasmatodea, Timemidae) and its consequences for host range. Biol. J. Linn. Soc., 52, pp 341-356.

Sandoval, C. P. and Nosil, P. (2005). Counteracting selective regimes and host preference evolution in ecotypes of two species of walking-sticks. Evolution 59:2405-2413 (Full Text)

Sandoval, C.P. and Vickery, V.R. (1996). Timema douglasi (Phasmatoptera:Timematodea), a new parthenogenetic species from southwestern Oregon and northern California, with notes on other species. Can. Entomol. 128:79-84.

Sandoval, C. & B. J. Crespi (2008). Adaptive evolution of cryptic coloration: the shape of host plants and dorsal stripes in Timema walking-sticks. Biol. J. Linn. Soc., 94, pp 1-5 (PDF)

Schwander T., Crespi B.J. (2009). Multiple direct transitions from sexual reproduction to apomictic parthenogenesis in Timema stick insects. Evolution 63, 84-103. (PDF)

Schwander T. , H. Lee, B.J. Crespi (2011). Molecular evidence for ancient asexuality in Timema stick insects. Curr. Biol., 21, pp. 1129–1134 (Full Text)

Schwander T., D. Arbuthnott, R. Gries, G. Gries, P. Nosil, & B. Crespi (2013). Hydrocarbon divergence and reproductive isolation in Timema stick insects. Evolutionary Biology 13:151 (Full Text)

Strohecker, H. F. (1966). New Timema from Nevada and Arizona. Pan-Pacific Entomologist, 42 (1) pp. 25-26. (Full Text)

Tinkham, E. R. (1942). A new californian species of Timema (Phasmodea: Timemidae) with zoogeographical notes. Bull. S. Calif. Acad. Sci. 41(2):72-79. pl. 14 (Read at BHL)

Vickery, V. R. & Sandoval, C. P. (1997). Timema bartmani (Phasmatoptera: Timematodea: Timematidae), a new species from southern California. The Canadian Entomologist 129:933-936

Vickery, V. R. & Sandoval, C. P. (1998). Timema monikensis, Species Nov. (Phasmatoptera: Timemmatidea: Timematidae), a new parthenogenetic species in California. Lyman Ent. Mus. & Res. Lab. Note 22.

Vickery V. R. & C. P. Sandoval (1999a). Two new species of Timema, One Parthenogenetic in California. J. Orthoptera Res. 8 (1) 45:47 (JSTOR)

Vickery V. R. & C. P. Sandoval (1999b). Timema coffmani (Phasmatoptera: Timematodea) a New Species from Arizona and Description of the Female of Timema ritensis. J. Orthoptera Res. 8 (1) 49:52 (JSTOR)

iNat page ▪ images from (3) ▪ Image of T. dorothea (ToL) ▪ Images of T. poppense males: [a] · [b]