We describe three new genera of cynipid oak gall wasps from the Nearctic: Burnettweldia Pujade-Villar, Melika & Nicholls, gen. nov., Nichollsiella Melika, Pujade-Villar & Stone, gen. nov., and Disholandricus Melika, Pujade-Villar & Nicholls, gen. nov. (Hymenoptera: Cynipidae: Cynipini). Burnettweldia includes five species, B. californicordazi Cuesta-Porta, Melika & Pujade-Villar, sp. nov., B. conalis (Weld), comb. nov., B. corallina (Bassett), comb. nov., B. plumbella (Kinsey), comb. nov., B. washingtonensis (Gillette), comb. nov.. Nichollsiella includes three species, N. arizonica (Cockerell), comb. nov., N. sulcata (Ashmead), comb. nov., and N. puigi Melika, Cuesta-Porta & Pujade-Villar, sp. nov.. Disholandricus includes four species, D. chrysolepidis (Ashmead), comb. nov., D. lasius (Ashmead), comb. nov., D. reniformis (McCracken & Egbert), comb. nov., D. truckeensis (Ashmead), comb. nov. The genus Paracraspis Weld, comb. rev. is re-established with three species, P. guadaloupensis (Fullaway), P. insolens (Weld), and P. patelloides (Trotter). Descriptions, re-descriptions, diagnoses, keys to genera and species are given, including data on DNA sequences, biology, phenology and distribution.

The Nearctic cynipid oak gall wasp genus Druon Kinsey comb. rev. is re-established, with 5 new species and 10 species previously placed in the genus Andricus Hartig 1840: D. alexandri Melika, Nicholls & Stone, sp. nov., D. flocculentum (Lyon), comb. nov., D. fullawayi (Beutenmüller), comb. nov., D. garciamartinonae Pujade-Villar, sp. nov., D. gregori Melika, Nicholls & Stone, sp. nov., D. hansoni Cuesta-Porta, Melika & Pujade-Villar, sp. nov., D. ignotum (Bassett), comb. nov., D. linaria Kinsey, comb. rev., D. pattoni (Bassett), comb. nov., D. protagion Kinsey, comb. rev. (D. malinum Kinsey, syn. nov., D. polymorphae Kinsey, syn. nov.), D. quercusflocci (Walsh), comb. nov., D. quercuslanigerum (Ashmead), comb. nov., D. receptum Kinsey, comb. rev., D. rusticum Kinsey, comb. rev. and D. serretae Pujade-Villar, Cuesta-Porta & Melika, sp. nov.. All species are known only from their asexual generation except for D. ignotum and D. quercuslanigerum, for which alternating asexual and sexual generations are known. The sexual generation of D. ignotum and a new morphological variety of D. quercuslanigerum from Mexico are both described for the first time. We provide descriptions, redescriptions, diagnoses, keys to species, DNA sequence data and analyses, and information on biology, phenology, and distribution. Additionally, four Andricus species with woolly galls and striato-reticulated metasomas are transferred to Striatoandricus Pujade-Villar: S. furnessulus, comb. nov., S. furnessae, comb. nov., S. guatemalensis, comb. nov., and S. tenuicornis, comb. nov.

The Nearctic cynipid oak gall wasp genus Feron Kinsey, comb. rev., is re-established with 34 species: F. albicomus (Weld, 1952), comb. nov., F. amphorus (Weld, 1926), comb. nov., F. apiarium (Weld, 1944), comb. nov., F. atrimentum (Kinsey, 1922), comb. nov., F. bakkeri (Lyon, 1984), comb. nov., F. caepula (Weld, 1926), comb. nov., F. californicum (Beutenmueller, 1911), comb. nov., F. clarkei (Bassett, 1890), comb. nov., F. comatum (Weld, 1952), comb. nov., F. crystallinum (Bassett, 1900), comb. nov., F. cylindratum (Kinsey, 1937), comb. nov., F. discale (Weld, 1926), comb. nov., F. discularis (Weld, 1926), comb. nov., F. dumosae (Weld, 1957), comb. nov., F. gigas (Kinsey, 1922), comb. nov., F. izabellae Melika, Nicholls & Stone, sp. nov., F. kingi (Bassett, 1900), comb. nov., F. parmula (Bassett, 1900), comb. nov., F. pattersonae (Fullaway, 1911), comb. nov., F. roberti Melika, Nicholls & Stone, sp. nov., F. rucklei Melika, Nicholls & Stone, sp. nov., F. scutellum (Weld, 1930), comb. nov., F. serranoae Pujade-Villar & Cuesta-Porta, sp. nov., F. splendens (Weld, 1919), comb. nov., F. stellare (Weld, 1926), comb. nov., F. stellulum (Burnett, 1974), comb. nov., F. sulfureum (Weld, 1926), comb. nov., F. syndicorum Pujade-Villar & Cuesta-Porta, sp. nov., F. tecturnarum (Kinsey, 1920), comb. nov., F. tetyanae Melika, sp. nov., F. tibiale Kinsey, 1937, comb. rev., F. tubifaciens (Weld, 1926), comb. nov., F. verutum Kinsey, 1937, comb. rev., and F. vitreum Kinsey, 1937, comb. rev. Most species are known only from the asexual generation; F. clarkei, F. comatum, and F. dumosae are known only from the sexual generation, while both generations are recognised for F. atrimentum, F. crystallinum, F. gigas, F. kingi, and F. pattersonae. Matching of alternate sexual and asexual generations is established for the first time for F. kingi and F. pattersonae (= Andricus pedicellatus (Kinsey, 1922), syn. nov.) based on molecular data (both cytb and ITS2 sequences). Morphological descriptions, re-descriptions, diagnoses, and a key to species are given, as well as data on DNA sequences, biology, phenology, and distribution.

Aphids are a serious pest for peach crops. They have traditionally been managed with insecticides, but there is increasing concern about the risk that insecticides pose to both humans and the environment. As a first step to use biological control in aphid management, we conducted a 3-year field survey in northeastern Spain to determine which parasitoids and hyperparasitoids were most prevalent on two aphids, Myzus persicae (Sulzer) and Hyalopterus spp. Koch, the most harmful to peach trees. We collected 11 parasitoid species from M. persicae, with Aphidius matricariae (Haliday) being the most abundant. Two parasitoid species were also collected from Hyalopterus spp., Aphidius transcaspicus Telenga and Praon volucre (Haliday). Hyperparasitoid species overlapped between these aphids but their relative abundances differed. We also discuss the possible impacts of hyperparasitoids on parasitoid populations. Our results suggest that it would be feasible to implement biocontrol methods for aphids in integrated pest management programmes in peach orchards. There are a number of primary parasitoid species associated with these aphids, and the nearby crops and wild vegetation in the vicinity and within the orchards may provide a suitable habitat for them. Additionally, some of them are commercially available and might be usable in augmentative releases.

A new gall wasp species, Cerroneuroterus yukawamasudai Pujade-Villar & Melika sp. nov., is described from China. The asexual generation induces leaf lenticular galls, and the sexual generation induces catkin galls on Q. acutissima and Q. variabilis. Sexual females and males are not described yet. Data on the diagnosis, distribution, and biology of the new species are provided, including a key to sexual and asexual females of all described Cerroneuroterus species. Previous misidentifications of host galls recorded in Japan are commented on. Molecular analyses were performed to assess the validity of the genus Cerroneuroterus and the affiliation of the new species.

The original description of Parandricus mairei Kieffer, 1906 included a misinterpretation of a relevant forewing trait. The species was subsequently transferred to the genus Andricus, despite presenting two very peculiar morphological characters, namely a simple tarsal claw and the absence of irradiating carinae on the lower face. Similarly, the original descriptions of Andricus deqingis Wang, Gui, Chen, 2013 and A. flavus Pujade-Villar, Wang, Guo & Chen, 2014 included some relevant mistakes. Here, we present the results of a molecular analysis that reveals that individuals of the three species are genetically very similar; supporting the proposal that A. mairei is a senior synonym of the other two species, A. deqingis n. syn. and A. flavus n. syn. In addition, our results indicate that Parandricus renders Andricus paraphyletic, which supports that Parandricus is a junior synonym of Andricus. We re-describe and illustrate the relevant characters of A. mairei and provide additional comments on the characters erroneously interpreted in the former descriptions and give notes about the biology and intraspecific variability.