Supplementary table 1: Phoretic egg parasitoids (update of Clausen 1976).

Egg parasitoid species / Host species / Attached body part / Transporting sex / Attracting cues / Host egg-laying / References
Scelionidae
Synoditella sp. / Dichromorpha viridis / Wings or hind legs / Gravid females / - / 12-60 eggs / Cited by Clausen 1976
Synoditella fulgidus / Chortoicetes terminifera / Abdomen / Ovipositing females / - / 30-60 eggs / Cited by Clausen 1976
Synoditella bisulcus / Melanoplus spec. / Abdomen / Females / Melanonic scars / Egg pods / Cited by Clausen 1976
Synoditella viatrix / Colemania sphenarioides / - / - / - / Gregarious / Cited by Clausen 1976
Synoditella viatrix / Neorthacris acuticeps milgirensis / Abdomen / Females / - / Egg pods / Cited by Clausen 1976
Lepidoscelio sp. / Neorthacris simulans / Abdomen / - / - / Egg pods / Cited by Clausen 1976
Mantibaria manticida / Mantis religiosa / Wings/genital plates / Both sexes / - / 100-300 eggs / Cited by Clausen 1976
Mantibaria seefelderiana / Mantis religiosa / Wings/genital plates / Both sexes / - / 100-300 eggs / Bin 1985
Telenomus beneficiens / Schoenobius incertulus / Wings / Females / - / Gregarious / Cited by Clausen 1976
Telenomus gracilis / Dendrolimus sibiricus / Thorax / - / - / Gregarious / Cited by Clausen 1976
Telenomus dendrolimusi / D. sibiricus albolineatus / Wings / - / - / Gregarious / Cited by Clausen 1976
Telenomus euproctidis / Euproctis taiwana
Euproctis pseudoconspersa / Anal tuft / Virgin females / Moth’s sex pheromone / 188.3 ± 24 eggs / Arakaki 1990; Arakaki et al. 1995; 1996
Telenomus calvus / Podisus maculiventris / Pronota and femora / Both sexes / Male pheromone, specific volatiles of mated females / 17-70 eggs / Aldrich et al. 1984; Bruni et al. 2000; Buschman and Whitcomb 1980; Orr et al. 1986
Telenomus sp. / Apantesis parthenice / Wings / Females / - / Gregarious / Platt 1985
Telenomus rowani / Scirpophaga innotata / Wings / - / - / About 100 eggs / Learmonth 1981
Telenomus transversus / Scirpophaga innotata / Wings / - / - / About 100 eggs / Bin and Johnson 1982
Telenomus sp. / Inachis io / Wings / Females / - / Gregarious / van Berkel, pers. comm.
Epinomus anoplocnemidis / Anoplocnemus curvipes / Head / - / - / Gregarious / Cited by Clausen 1976
Asolcus sulmo / Cantheconidea gaugleri / Head, antennae, thorax, legs / - / - / Gregarious / Cited by Clausen 1976
Boyeria vinosa / Calotelea n. sp. boyeria / Thorax / Females / - / - / Cited by Clausen 1976
Protelenomus sp. / Anoplocnemis phasiana / Hind femora in males
Antennae in females / Both sexes / - / Eggs in clumps / Kohno 2002
Trichogrammatidae
Oligosita xiphidii / Conocephalus longipennis / Hind wings / Females / - / Egg pods / Cited by Clausen 1976
Oligosita brevicilia / Neoconocephalus sp. / Hind wings / - / - / Egg pods / De Santis and Cicchino 1992
Pseudoxenufens forsysthi
(=Xenufens sp.) / Caligo eurilochus / Hind wings / Both sexes / - / Small batches / Cited by Clausen 1976
Pseudoxenufens forsysthi / Opsiphanes cassina / Abdomen / - / - / In clusters / Yoshimoto 1976
Brachista efferiae
Brachista fisheri / Efferia efferiae
Efferia fisheri / Near base of halteres / Females / - / - / Pinto 1994
Trichogramma dendrolimi / Dendrolimus sibiricus albolineatus / Wings / - / - / Gregarious / Cited by Clausen 1976
Trichogramma brassicae / Pieris brassicae, P. rapae / Wings / Mated females / Antiaphrodisiac / Gregarious / Fatouros et al. 2005; Huigens et al. 2010
Trichogramma evanescens / P. brassicae, P. rapae / Wings / Mated females / Antiaphrodisiac / Single / Huigens et al. 2009; 2010
Encyrtidae
Taftia prodeniae / Saissetia/ Pseudococcus / Bases of antennae / Ant workers / - / Egg clutches in cottony sacs / Cited by Clausen 1976
Eupelmidae
Anastatus bifasciatus / Porthetria dispar / Abdomen / Females / - / 100-1000 eggs / Cited by Clausen 1976
Eulophidae
Emersonella niveipes / Stolas sp.
Banotochara pavonia / Elytrae / Ovipositing females / - / Stolas: 10-50 / Carroll 1978
Chrysocharodes rotundiventris / Mecistomela marginata / - / Mated females / - / Single/Gregarious / Macedo et al. 1990
Grassator viator / Naupactus xanthographus / Prothorax / - / - / Egg clusters / Cited by Clausen 1976
Torymidae
Podagrion fraternum / Mantis prasina
Polyspilota pustulata / Hind wings / Females / - / Egg masses / Cited by Clausen 1976

Supplementary table 2: Solitary and gregarious lepidopteran species collected during our survey of which there are reports on egg parasitism and/or phoresy by Trichogramma species. Lepidopteran species on which phoretic wasps have been found are mentioned in bold. In case phoretic individuals of a Trichogramma species were collected on a given lepidopteran species during our survey, the species name is also mentioned in bold. N = Number of adults collected during our survey.

Host species / N / Host egg-laying / Egg parasitism / Wasps/egg / References on egg parasitism
Butterflies
Aglais urticae / 9 / Gregarious / T. semblidis / - / Polaszek 2010
Coenonympha pamphilus / 3 / Solitary / T. brassicae / ± 4 / Babendreier et al. 2003a
Inachis io / 20 / Gregarious / T. dendrolimi / ± 2 / Polaszek 2010
Maniola jurtina1 / 338 / Solitary / T. brassicae / ± 4 / Babendreier et al. 2003a; Babendreier et al. 2003b
Papilio machaon / 2 / Gregarious / T. brassicae, T. chilonis / ± 12 / Babendreier et al. 2003a;b; Polaszek 2010
Pieris brassicae1 / 71 / Gregarious / T. evanescens, T. brassicae / ± 4 / Gardner et al. 2007; Mustata and Mustata 2000; van Heiningen et al. 1985
Pieris napi1 / 373 / Solitary / T. evanescens, T. brassicae / ± 4 / Babendreier et al. 2003a; Mustata and Mustata 2000
Pieris rapae1 / 253 / Solitary / T. evanescens, T. brassicae, and T. buesi / ± 3 / Abbas 1989; Abbas 1989; Krnjajic et al. 1997; Lundgren et al. 2002; Mustata and Mustata 2000; Pak 1988; Parker 1970
Polyommatus icarus / 93 / Gregarious / T. brassicae / ± 2 / Babendreier et al. 2003a
Vanessa atalanta / 42 / Solitary / T. brassicae / ± 4 / Babendreier et al. 2003a
Vanessa cardui1 / 122 / Solitary / T. euproctidis andT. bourarachae / - / Polaszek 2010
Zygaena filipendula / 3 / Gregarious / T. brassicae / - / Babendreier et al. 2003a
Moths
Agrotis exclamationis / 11 / - / T. brassicae, T. buesi, T. cacoeciae, T. dendrolimi, and T. evanescens / - / Polaszek 2010
Agrotis ipsilon / 1 / Gregarious / T. brassicae, T. buesi, T. cacoeciae, T. dendrolimi, and T. evanescens, / - / Polaszek 2010; Shalaby et al. 2000
Agrotis segetum / 6 / Solitary / T. brassicae, T. buesi, T. cacoeciae, T. dendrolimi, T. embryophagum, T. evanescens, T. euproctidis, T. pintoi, T. principium, T. semblidis, and T. turkeiensis / - / Polaszek 2010; Ram et al. 1995
Autographa gamma / 8 / Solitary / T. brassicae, T. buesi, T. cacoeciae, T. cordubensis, T. dendrolimi, T. evanescens, T. mirabile, T. rossicum, and T. savalense / ± 1 / Klug and Meyhöfer 2009; Polaszek 2010
Deilephila elpenor / 1 / Solitary / T. brassicae / ± 21 / Babendreier et al. 2003a; Polaszek 2010
Erannis defoliaria / 1 / Gregarious / T. evanescens / - / Glavendekic 2010; Polaszek 2010
Hypena proboscidalis / 19 / Gregarious / T. semblidis / - / Polaszek 2010
Lymantria dispar / 3 / Gregarious / T. dendrolimi and T. evanescens / - / Polaszek 2010
Mamestra brassicae / 1 / Gregarious / T. achaeae, T. buesi, T. cacoecidae, T. chilonis, T. chilotraeae, T. dendrolimi, T. evanescens, T. brassicae, T. gicai, T. lacustre, T. leptoparameron, T. leucaniae, T. misiae, T. papilionis, T. piceum, T. pintoi, T. principium, T. semblidis. T. trjapitzini, T. tshumakovae, T. ussuricum / ± 2 / Gardner et al. 2007; Takada et al. 2001Pavlík 1993; Polaszek 2010; Ram et al. 1995; Takada et al. 2001; van Rijswijk 2000
Noctua pronuba / 51 / Solitary / T. cacoeciae, T. cordubensis, T. evanescens, and T. semblidis / ± 2 / Polaszek 2010; Roriz et al. 2006
Pheosia tremula / 1 / Gregarious / T. dendrolimi / - / Polaszek 2010
Phlogophora meticulosa2 / 7 / Solitary / T. cordubensis and T. evanescens / ± 2 / Polaszek 2010; Roriz et al. 2006
Xanthia togata / 1 / - / T. semblidis / - / Polaszek 2010
Xestia baja2 / 2 / Gregarious / - / - / -
Xestia c-nigrum1 / 66 / Solitary / T. cordubensis / ± 2 / Roriz et al. 2006

1 Phoretic wasps found during our survey 2 Phoretic Trichogramma sp. wasps found in the Netherlands by J. Voogd (personal communication)

Supplementary table 3: Collected solitary and gregarious butterfly species. N = Number of adults collected during our survey.

Butterfly species / N / Egg-laying
Aglais urticae / 9 / Gregarious
Anthocharis cardamines / 3 / Solitary
Aricia agestis / 4 / Solitary
Celastrina argiolus / 5 / Solitary
Coenonympha pamphilus / 3 / Solitary
Gonepteryx rhamni / 11 / Solitary
Inachis io / 20 / Gregarious
Lasiommata megera / 1 / Solitary
Lycaena phlaeas / 23 / Solitary
Maniola jurtina / 338 / Solitary
Ochlodes faunus / 1 / Solitary
Papilio machaon / 2 / Gregarious
Pararge aegeria / 17 / Solitary
Pieris brassicae / 72 / Gregarious
Pieris napi / 373 / Solitary
Pieris rapae / 253 / Solitary
Plebeius agestis / 38 / Gregarious
Polygonia c-album / 9 / Solitary
Polyommatus icarus / 93 / Gregarious
Pyronia tithonus / 19 / Gregarious
Thymelicus lineola / 11 / Gregarious
Vanessa atalanta / 42 / Solitary
Vanessa cardui / 122 / Solitary
Zygaena filipendulae / 3 / Gregarious

Supplementary table 4: Collected solitary and gregarious moth species. N = Number of adults collected during our survey.

Moth species / N / Egg-laying
Abrostola triplasia / 2 / -
Agrochola lota / 1 / -
Agrochola macilenta / 1 / -
Agrotis exclamationis / 11 / -
Agrotis ipsilon / 2 / -
Agrotis puta / 10 / Gregarious
Agrotis segetum / 6 / Solitary
Amphipyra pyramidea / 14 / Solitary
Atethmia centrago / 4 / Gregarious
Autographa gamma / 8 / Solitary
Axylia putris / 18 / -
Cabera exanthemata / 6 / -
Cabera pusaria / 4 / -
Campaea margaritata / 12 / Gregarious
Camptogramma bilineata / 3 / Solitary
Cerapteryx graminis / 1 / -
Chloroclysta citrata / 1 / -
Chloroclysta truncata / 11 / Gregarious
Colostygia pectinataria / 2 / Gregarious
Colotois pennaria / 1 / -
Cosmia trapezina / 1 / -
Cosmorhoe ocellata / 1 / -
Cossus cossus / 1 / Gregarious
Craniophora ligustri / 2 / Gregarious
Cucullia umbratica / 1 / -
Cyclophora albipunctata / 1 / -
Cyclophora linearia / 2 / Solitary
Cyclophora punctaria / 1 / -
Deilephila elpenor / 1 / Solitary
Diachrysia chrysitis / 27 / -
Diarsia rubi / 22 / -
Earias clorana / 1 / -
Ecliptopera silaceata / 1 / -
Ectropis crepuscularia / 1 / -
Eilema complana / 2 / -
Epione repandaria / 4 / Solitary
Epirrhoe alternata / 43 / -
Erannis defoliaria / 1 / Gregarious
Eupithecia centaureata / 5 / -
Eupithecia indigata / 2 / -
Eupithecia succenturiata / 2 / -
Eupithecia tripunctaria / 1 / -
Gortyna flavago / 1 / -
Habrosyne pyritoides / 12 / -
Hoplodrina ambigua / 1 / Solitary
Hoplodrina blanda / 2 / -
Hoplodrina octogenaria / 1 / -
Hydraecia micacea / 3 / -
Hylaea fasciaria / 1 / -
Hypena proboscidalis / 19 / Gregarious
Idaea aversata / 12 / -
Idaea biselata / 1 / -
Lacanobia oleracea / 10 / Gregarious
Ligdia adustata / 1 / -
Lomaspilis marginata / 8 / -
Lomographa temerata / 2 / -
Lymantria dispar / 3 / Gregarious
Macaria alternata / 10 / -
Macaria liturata / 6 / -
Macaria notata / 5 / -
Macdunnoughia confusa / 1 / -
Mamestra brassicae / 1 / Gregarious
Mesapamea didyma / 1 / -
Mesapamea secalis / 4 / -
Mesoligia furuncula / 7 / -
Mythimna albipuncta / 5 / -
Mythimna impura / 1 / -
Mythimna l-album / 1 / -
Noctua comes / 6 / -
Noctua interjecta / 11 / -
Noctua janthe / 2 / -
Noctua janthina / 5 / -
Noctua pronuba / 51 / Solitary
Notodonta dromedarius / 2 / -
Notodonta ziczac / 1 / Solitary
Ochropleura plecta / 104 / Gregarious
Opisthograptis luteolata / 18 / Gregarious
Orthosia cerasi / 1 / Gregarious
Orthosia gothica / 2 / Gregarious
Orthosia incerta / 1 / -
Paradrina clavipalpis / 1 / -
Peribatodes rhomboidaria / 13 / -
Perizoma alchemillata / 4 / -
Pheosia tremula / 1 / Gregarious
Phlogophora meticulosa / 7 / Solitary
Phragmatobia fuliginosa / 6 / -
Plusia festucae / 1 / -
Polypogon strigilata / 1 / -
Pterostoma palpina / 1 / -
Ptilodon capucina / 6 / Solitary
Rivula sericealis / 14 / -
Spilosoma lubricipeda / 1 / Gregarious
Thaumetopoea processionea / 7 / Gregarious
Thera britannica / 4 / -
Tholera decimalis / 3 / Solitary
Thyatira batis / 7 / -
Timandra comae / 7 / Gregarious
Triodia sylvina / 2 / -
Watsonalla binaria / 8 / Solitary
Watsonalla cultraria / 1 / Solitary
Xanthia citrago / 2 / -
Xanthia icteritia / 1 / -
Xanthia togata / 1 / -
Xanthorhoe biriviata / 1 / -
Xanthorhoe designata / 2 / -
Xanthorhoe ferrugata / 8 / -
Xanthorhoe fluctuata / 2 / Gregarious
Xanthorhoe spadicearia / 1 / -
Xestia baja / 2 / Gregarious
Xestia c-nigrum / 66 / Solitary
Xestia xanthographa / 34 / -

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