The larval head of a Phycosecis species is described and illustrated. Characters are compared to those found in larvae of other groups of Cucujiformia. Monophyly of all cleroid families examined is supported by several apomorphic features at least partly correlated with predacious habits: antennae directed anteriad, absence of the mandibular mola, presence of a pedunculate seta on the mala, presence of a median endocarina, origin of antennal muscles exclusively from the head capsule, and presence of a weakly pigmented, parallel-sided gular plate. A possible apomorphy of Cleroidea excluding Phloiophilidae is the parallel-sided, prognathous head. A sister-group relationship between Phycosecidae and Melyridae is supported by the presence of a plumose lacinia mobilis and secondary loss of the median endocarina. A monophylum comprising Cleridae + Chaetosomatidae is characterised by a strongly elongated, sclerotised larval gula, the strongly protracted position of the ventral mouthparts, and a cardo as long as or longer than the stipes. Monophyly of Trogossitidae is only weakly supported. Several apomorphies indicate a sister-group relationship between Cleroidea and Nitidulidae. These two taxa are characterised by a fully developed maxillolabial complex, an elongated prepharyngeal tube, and tergal sclerotisation restricted to the prothorax and tergite IX. A tentorial bridge completely separated from the remaining tentorium, and a maxillolabial complex with partly restricted motility of the maxilla are shared derived features of larvae of Cleroidea, Nitidulidae, Coccinellidae and Endomychidae. An unusual attachment of a part of the tentoriostipital muscle to the floor of the prepharyngeal tube is found in all cleroid and cucujoid larvae examined. Cleroidea are a well-defined monophyletic group and may form a monophylum together with a paraphyletic assemblage of Cucujoidea. A close relationship between Cleroidea and Lymexylidae is refuted.

The classification of the nine world species of Pytho Latreille is reviewed by study of adult, larval, and pupal stages. Keys are provided for separation of species in these three life stages. Taxonomic changes (senior synonym in brackets) include synonymy of P. fallax Seidlitz 1916 [= P. niger Kirby 1837]; P. americanus Kirby 1837 [= P. planus (Olivier 1795)]; P. deplanatus Mannerheim 1843 is transferred from a junior subjective synonym of P. depressus (Linnaeus 1767) to a junior subjective synonym of P. planus (Olivier 1795). Lectotype designations are provided for the following: P. seidlitzi Blair 1925; P. nivalis Lewis 1888; P. niger Kirby 1837; P. fallax Seidlitz 1916; P. abieticola J. Sahlberg 1875; and P. americanus Kirby 1837. Eight larval stage, and 12 adult stage characters were selected for cladistic analysis. Lacking out-group material, pupal characters were not analysed. Character states were polarized using a generalized out-group composed of the three other genera of Pythinae (all monobasic). Phylogenetic analysis based on these 18 characters suggests four monophyletic species-groups: P. seidlitzi group (P. seidlitzi Blair — North America); P. kolwensis group (P. strictus LeConte – North America, P. kolwensis C. Sahlberg —Fennoscandia and the U.S.S.R., P. nivalis Lewis — Japan); P. niger group (P. niger Kirby — North America, P. abieticola J. Sahlberg — Europe, P. jezoensis Kôno — Japan); P. depressus group [P. planus (Olivier, 1795) — North America, P. depressus (Linnaeus, 1767) — Europe and the U.S.S.R.]. Larval stage synapomorphies are relatively more important in defining the species-groups than are those of the adult stage. The ancestor of Pythidae may have been associated with Coniferae as early as the Jurassic. The common ancestor of Northern Hemisphere Pythinae became isolated upon Laurasia once separation from Gondwanaland occurred near the end of the Jurassic. Two of the species-groups have similar disjunctions in North America, Europe, and Japan. The relatively eastern distributions of the North American member of each suggests that the ancestor of each species-group was Euramerican, and underwent vicariance with the opening of the North Atlantic in the Middle Cretaceous. The present distribution of both species-groups is thought to have been caused by the same vicariant event. The ancestor of the P. depressus group, which is presently circumboreal, was probably widespread and could have been Asiamerican in distribution. In the middle to late Tertiary, evidence suggests that Beringia was covered with coniferous forest, and the ancestor of the P. depressus group probably extended across this land bridge. Final separation between any North American and European/Asian species occurred in the Late Miocene or Pliocene, when a cooling climate made possible the evolution of treeless tundra in the north.

Three species of robber flies (Asilidae) are recorded as preying on workers of Pogonomyrmex harvester ants in eastern New Mexico and western Texas: Cerotainiops abdominalis, Saropogon combustus, and Saropogon pritchardi. Of 379 prey records for C. abdominalis, 66% were Pogonomyrmex workers. Two species of Saropogon were collected in association with a large number of harvester ant workers: S. combustus (40% of 263 prey records) and S. pritchardi (94% of 288 prey records). All three species show a statistical preference for Hymenoptera, specifically for harvester ant workers, and avoidance of Diptera, Hemiptera, Lepidoptera, and Orthoptera prey. A brief review of invertebrate predators of Pogonomyrmex workers is given, with emphasis on asilid predators. For the three asilid predators mentioned in the article, seasonality, observed behaviors, and a list of known prey taxa are included.

Currently, the Canadian fauna of Eustrophinae consists of 7 species in 5 genera, as follows: Pseudoholostrophus impressicollis (LeConte), P. discolor (Horn); Ho