The genus Holocera, is related to the lecaniine Coccidae and is predaceous. Some representatives are thought to be scavengers rather than predators of living scale insects. Holcocera pulverea Meyr., attacking the lac insect in India, causes economic loss to the lac industry, not only through its destruction of living scales but through the infestation of stored lac. At times the field damage reaches 25-30%. Glover (1933) found that the eggs were laid singly on adult female scales, empty male cocoons, or twigs having a heavy growth of sooty-mold fungus, produced by the scale infestation. Younger larvae feed on the body contents and waxy covering of scale insects. They move from one scale to another, building a silken tunnel or web through the mass. A maximum of 45 adult female scales have been found killed, and the wax covering partially destroyed, by each larva during its feeding. There are 5 generations annually, and winter is spent principally in the egg stage. Eggs seem to be very susceptible to changes in weather, for there is high winter mortality. Also, the majority of eggs laid during June are killed by high temperatures of the season (Glover 1933).
In the western part of North America, H. iceryaella Riley attacks Lecanium persicae F. and other lecaniine and diaspine Coccidae. There is some uncertainty as to whether feeding is mainly on living or dead scales. Basinger (1924) reported that the larvae of this species feed on citrus fruit in California. They construct holes or channels into oranges that are similar to those made by Tortrix citrana Fern. Blastobasis transcripta Meyr. is a natural enemy of Ripersia in India. Zenodochium coccivorella Ch. is an internal parasitoid of the gall-like females of Kermes in Florida, but it was believed to be more probably a specialized predator on the eggs in the egg chamber, and restricted to the product of a single female (Clausen 1940/1962).
This family of moths is in the superfamily Gelechioidea. Its species can be found almost anywhere in the world, though in some places they are not native but introduced by humans. In some arrangements, these moths are included in the case-bearer family (Coleophoridae) as subfamily Blastobasinae. The Symmocidae are sometimes included in the Blastobasidae (particularly if both are included in Coleophoridae) as subfamily or tribe.
The group around Holcocera is often separated as subfamily Holcocerinae (or tribe Holcocerini) from the Blastobasis lineage (which correspondingly become a subfamily, or a tribe Blastobasini). While this seems far more reasonable than some of the more extreme arrangements sometimes seen in Gelechioidea taxonomy and systematics, the relationships among Blastobasidae genera are not yet sufficiently studied to allow a well-supported subdivision of this family.
The imagines (adults) are small, slender moths which at a casual glance lack conspicuous and characteristic features – noted entomologist Edward Meyrick once described the group as "obscure and dull coloured moths, decidedly the least attractive family of Lepidoptera". Their coloration is usually reddish-brown, without crisp streaks or large wingspots.
The head is smooth, with moderately long antennae (slightly more than half as long as the forewings) which are each situated halfway down the head. As usual for moths, the antennae do not have clubs; even in the males they are smooth or almost so and not at all comb-like. The antenna base bears a small brush of dense hairs and is flat, with a concave underside and may cover part of the compound eyes. The Blastobasidae have few or no bristles on the compound eyes, no ocelli, and probably lack chaetosemata too. The mouthparts are well-developed and moderately specialized, with 4-segmented folding maxillary palps, long labial palps and a long proboscis with a scaly base. The tibiae of the forelegs are enlarged at the end, those of the middle legs two spurs, and those of the hundlegs 4 spurs and many long thin hairs.
Wingspan is about one to two dozen millimeters, more than ten times as much as the thorax width. The forewings lack a tornus and are about 4-5 times as long as they are wide, with a convex outer margin and a rather blunt tip. The round-tipped hindwings are very narrow, of equal or somewhat less length as the forewings, to which they are joined with a frenulum. The edge of the hindwings is surrounded by a fringe of hairs about two times as long as the wing is wide.
The wing venation of forewings and hindwings differs. The forewing has 12 veins altogether, with two anal veins – vein 1b and 1c, the former of which forks proximally – and a distally complete tubular vein (1c). The transverse vein is complete, and the discal cell has no tubular vein running through its middle. By contrast, the hindwings have 7 or 8 veins. Their anal veins are 1b and 1c like on the forewings; they lack vein 1a but also have the tubular vein 1c. Vein 1b may fork as in the forewings or remain unbranched, while a transverse vein may be present or not. Usually, 5 veins arise from the hindwing cell, of which the fourth and fifth are proximally joined; Blastobasis however might only have 4 cell veins, with veins 3 and 5 joined and vein 4 missing, but this is not universally accepted. Hindwing vein 8 either runs along the upper cell margin initially and anastomizes with it; possibly, it arises from the cell margin in some species, but in neither case it runs close to vein 7.
Most of the estimated 32 genera of Blastobasidae presently recognized are small or even monotypic, though Auximobasis and Pigritia are fairly diverse and Blastobasis and Holcocera are quite large. Such an arrangement is suspicious of not representing the true phylogeny of the family adequately; with few species having been compared in sufficient detail in recent times, it is to be expected that as better data becomes available the two large genera will be split up, and/or several small genera will not be maintained as distinct. Thus, the following list is likely to change in the future.
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