The development of a true insect society among the Hymenoptera is dependent on a differentiation among the females between individuals with well-developed ovaries (" queens ") whose special function is reproduction; and individuals with reduced or aborted ovaries (" workers ") whose duty is to build the nest, to gather food and to tend and feed the larvae.
Meinert, who endeavoured to compare them with the tegulae of Hymenoptera, but the older view was securely established by the demonstration in pupal elytra by J.
Ants form a distinct and natural family (Formicidae) of the great order Hymenoptera, to which bees, wasps and sawflies also belong.
Such " workers " are essential to the formation of a social community of Hymenoptera, and their wingless condition among the ants shows that their specialization has been carried further in this family than among the wasps and bees.
It is interesting and suggestive that in a few families of digging Hymenoptera (such as the Mutillidae), allied to the ants, the females are wingless.
(For the so-called " white ants,"which belong to an order far removed from the Hymenoptera, see Termite.) Structure.
Injurious insects occur among the following orders: Coleoptera, Hymenoptera, Lepidoptera, Diptera, Hemiptera (both heteroptera and homoptera), Orthoptera, Neuroptera and Thysanoptera.
Another group of Hymenoptera occasionally causes much harm in fir plantations, namely, the Siricidae or wood-wasps, whose larvae burrow into the trunks of the trees and thus kill them.
P. Marchal has (1904) described this power in two small parasitic Hymenoptera - a Chalcid (Encyrtus) which lays eggs in the developing eggs of the small moth Hyponomeuta, and a Proctotrypid (Polygnotus) which infests a gall-midge (Cecidomyid) larva.
His classification was founded mainly on the nature of the wings, and five of his orders - the Hymenoptera (bees, ants, wasps, &c.), Coleoptera (beetles), Diptera (two-winged flies), Lepidoptera (moths and butterflies), and Hemiptera (bugs, cicads, &c.) - are recognized to-day with nearly the same limits as he laid down.
To the Lias also can be traced back the Neuroptera, the Trichoptera, the orthorrhaphous Diptera and, according to the determination of certain obscure fossils, also the Hymenoptera (ants).
In Tertiary times the higher Diptera, besides Lepidoptera and Hymenoptera, referable to existing families, become fairly abundant.
Fragmentary as the records are, they show that the Exopterygota preceded the Endopterygota in the evolution of the class, and that among the Endopterygota those orders in which the greatest difference exists between imago and larva - the Lepidoptera, Diptera and Hymenoptera - were the latest to take their rise.
The affinities of the Hymenoptera afford another problem of much difficulty.
From the evidence of fossils it seems that the higher sub-order - Apocrita - can be traced back to the Lias, so that we believe the Hymenoptera to be more ancient than the Diptera, and far more ancient than the Lepidoptera.
We would trace the Hymenoptera back therefore to the primitive endopterygote stock.
In some way it is assured among the highest of the Hexapoda - the Lepidoptera, Diptera and Hymenoptera - that the larva finds itself amid a rich food-supply.
But since ants are not persecuted by these two families of Hymenoptera, the greatest enemies spiders have to contend with, it is evident that mimicry of ants is of supreme advantage to spiders.
Orders: Aptera, Diptera, Hemiptera, Lepidoptera, Hymenoptera, Neuroptera, Orthoptera, Coleoptera.
Orders: Myriapoda, Thysanura, Parasita, Suctoria, Coleoptera, Orthoptera, Hemiptera, Neuroptera, Hymenoptera, Lepidoptera, Rhipiptera, Diptera.
Orders: Coleoptera, Orthoptera, Neuroptera, Hymenoptera, Lepidoptera, Hemiptera, Diptera, Rhipiptera, Anopleura, Thysanura.
There are 8 families of Coleoptera, 6 of Orthoptera, 23 of Hymenoptera, 14 of Lepidoptera and 7 of Diptera.
The relationship of the Hymenoptera to other orders of insects is discussed in the article Hexapoda, but it may be mentioned here that in structure the highest members of the order are remarkably specialized, and that in the perfection of their instincts they stand at the head of all insects and indeed of all invertebrate animals.
About 30,000speciesof Hymenoptera are now known.
A large number of Hymenoptera are, however, entirely wingless - at least as regards one sex or form of the species.
In female Hymenoptera the typical insectan.
The sucking tongue of the Hymenoptera has often been compared with the hypopharynx of other insects.
Sharp, however, the hypopharynx is present in all Hymenoptera as a distinct structure at the base of the " tongue," which must be regarded as representing the fused laciniae of the second maxillae.
The wings in the Hymenoptera show a marked reduction in the number of nervures as compared with more primitive insects.
Among many of the smaller Hymenoptera we find that the wings are almost destitute of nervures.
As regards their life history, all Hymenoptera undergo a " complete " metamorphosis.
The legs of Hymenoptera are of the typical insectan form, and the foot is usually composed of five segments.
In the different families of the Hymenoptera, there are various modifications of the ovipositor, in accord with the habits of the insects and the purposes to which the organ is put.
Most male Hymenoptera have processes which form claspers or genital armature.
The crop is followed by a proventriculus which, in the higher Hymenoptera, forms the so-called " honey stomach," by the contraction of whose walls the solid and liquid food can be separated, passed on into the digestive stomach, or held in the crop ready for regurgitation into the mouth.
Thus we find throughout the order a degree of care for offspring unreached by other insects, and this family-life has, in the best known of the Hymenoptera - ants, wasps and bees - developed into an elaborate social organization.
Reference has been already made to the various methods of feeding practised by Hymenoptera in the larval stage, and the care taken of or for the young throughout the order leads in many cases to the gathering of such food by the mother or nurse.
Most Hymenoptera are of moderate or small size, the giants of the order - certain saw-flies and tropical digging-waspsnever reach the bulk attained by the largest beetles, while the wing-spread is narrow compared with that of many dragonflies and moths.
Hymenoptera are probably less widely distributed than Aptera, Coleoptera or Diptera, but they are to be found in all except the most inhospitable regions of the globe.
It is of interest that the waters have been invaded by the parasitic group of the Hymenoptera, since in number of species this is by far the largest of the order.
- Very little is known of the history of the Hymenoptera previous to the Tertiary epoch, early in which, as we know from the evidence of many Oligocene and Miocene fossils, all the more important families had been differentiated.