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Thrips calcaratus
Fig. 1


Fig. 2


Fig. 3

Fore tarsus

Fig. 4


Fig. 5


Fig. 6


Fig. 7

Tergites 6-7

Fig. 8



Fig. 1: Antenna (inset: III. and IV. antennal segment)
Fig. 2: Head dorsal with ocellar triangle
Fig. 3: Fore tarsus  
Fig. 4: Pronotum
Fig. 5: Meso- and metanotum
Fig. 6: Forewing
Fig. 7: Tergites VI and VII
Fig. 8: Tergites VIII-X

Taxonomic Information

Thrips calcaratus Uzel, 1895

Common name:
Basswood thrips

Present taxonomic position:
Family: Thripidae Stephens, 1829
Subfamily: Thripinae (Stephens) Karny, 1921
Genus: Thrips Linneaeus, 1758


Species Recognition

General information about the genus Thrips:
There are about 280 species currently recognized in the genus Thrips making this genus one of the largest groups within the Thysanoptera. They are separated from other genera in having the following characters, antenna comprising 7 or 8 segments with segments III and IV containing forked sense cones, the head has two pairs of ocellar setae (II and III), pair I is missing, the pronotum with four long setae on the posterior margin, forewing 1st vein usually has a row of setae interrupted by gaps, on lateral sides of abdominal tergites V to VIII there are paired ctenidia, abdominal tergite VIII with ctenidia posterior to the spiracles.

Typical character states of Thrips calcaratus:

Body color
Mainly brown

Number of antennal segments: 7
Segment IV - forked sensorium: scarcely extending beyond base of segment V
Segments II and III shape: more or less symmetric
Segments III & IV sensoria: emergent and forked
Base of sensorium on antennal segment VI: no more than 2 times as wide as base of nearest seta
Terminal antennal segments: rarely elongate

Distance between bases of ocellar setae III: greater than width of first ocellus
Head shape between compound eyes: not prolonged
Ocellar setae III on head: arising on anterior margin of, or in front of, ocellar triangle
Postocular setae I: absent
Surface of head, pronotum and fore legs: without strong reticulate sculpture
Ocellar setae I in front of anterior ocellus: absent

Number of pairs of elongate pronotal setae: 0-3
Number of pairs of elongate posteroangular pronotal setae: 2
Pronotum shape: rectangular
Number of pairs of pronotum posteromarginal minor setae: 2-3
Number of pairs of pronotum anteromarginal minor setae: 2-4

Mesothoracic endofurca: with median spinula

Metanotal median area sculptured lines: transverse at anterior, but longitudinal and parallel on posterior half
Metanotal median setae length: longer than lateral metanotal setae
Metanotal median setae position: arising behind anterior margin
Metanotum: without campaniform sensilla
Metanotum major sclerite: with two major sclerites, metascutum and metascutellum
Metanotum median area: with no equiangular reticulation
Metanotum sculpture: without dominant sculptured triangle medially
Metathoracic endofurca: transverse, sometimes with simple median spinula

Wings: present and more than half as long as abdomen
First vein of forewing: distinct from costal vein
Forewing anterior margin: with setae and cilia but cilia longer than setae
Forewing clavus: terminal veinal seta longer than subterminal seta
Forewing color: uniformly dark or shaded, but with base (or sub-base) pale or uniformly pale or weakly shaded
Forewing costal fringe of cilia: arising at anterior margin of wing
Forewing costal setae at middle of wing: shorter than median width of wing
Forewing first vein setal row: incomplete, with setae not closely and uniformly spaced
Forewing posterior margin cilia: undulated near apex
Forewing second vein setal row: complete, with setae closely and uniformly spaced
Forewing surface: not reticulate
Forewings: with veins, setae and microtrichia

Fore tarsus inner apex: with small pointed tooth
Fore tibial apex: not extending around fore tarsus - with small curved claw ventrolaterally
Mid and hind tarsi: with two segments

Pleurotergal discal setae: absent
Abdominal pleurotergites: not covered in microtrichia
Abdominal segment X: never tubular, longitudinally incomplete ventrally in both sexes
Abdominal sternite II: with marginal setae but no discal setae
Abdominal sternite III of female: without glandular areas
Abdominal sternite VII: with discal setae present on median area
Abdominal sternite VII median marginal setae: arising in front of margin
Abdominal sternites IV , V and VI: with discal setae present medially as well as marginal setae
Number of lateral marginal setae on abdominal tergite II: 4
Abdominal tergites: without curved wing-retaining setae
Abdominal tergites IV & V median setal pair: much shorter than distance between their bases
Abdominal tergites V-VII: with pair of ctenidia laterally
Number of discal setae on sternite V: 3-9
Setae on abdominal tergite X: slender
Surface of lateral thirds of abdominal tergites: without regular rows of fine microtrichia
Ctenidia on tergite VIII: posteromesad to spiracle
Tergite VIII posteromarginal comb of microtrichia: present, complete medially
Tergite VIII posteromarginal microtrichia: short and irregular in length



Life history:
As with other thrips species the life cycle from egg to adult is dependent on temperature. The full cycle can take about 15 days (Lewis, 1973) to over a month and adults may live for more than one month producing several generations in one year depending on seasonal weather. With greenhouse temperatures the developmental time from egg to adult can decrease to about one week.

Host plants:
Tilia americana

Vector capacity:
None identified

Current known distribution:
Africa, Asia, Australia, New Zealand, Central and South America, Europe, North America

Additional notes:
Thrips calcaratus is known as a pest on basswood (Tilia americana) in north eastern US near the great lakes. The damaged caused from its feeding results in premature bud drop and leaf scarring.


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