88 



HYMENOPTERA 



unprovided for : as a result many of the helpless grubs died, and 

 others were in a state of starvation, when a strange queen-hornet 

 appeared, associated itself with the comb, and, adopting the orphan 

 brood, nourished them and brought them to their full size. 



We have ah-eady alluded to the fact that, so far as external 

 structure is concerned, there is no great difference between the 

 social and the solitary wasps. Both, too, run through analogous 

 series of forms and colours, and the genus Ischnugaster (Fig. o4) 

 seems to connect the two groups by both its structure and mode 

 of life. The social habits are in many species only inferred, and 

 with greater knowledge will probably prove fallacious as a guide 

 to classification ; indeed we have already said that in the genus 

 Vespa — perhaps the most perfectly social of all the wasps — there 



is one species that has no worker, 

 and that lives, it is supposed, as 

 a parasite, in the nests of its 

 congeners. For this species, V. 

 (mstriaca, it has been proposed to 

 create a separate genus, Fsrudo- 

 ■vespa, on account of this peculiarity 

 of habit, although no structural 

 character has been detected tluit 

 could distinguish it. De Saussure 

 has stated his conviction that 

 workers do not exist in some of 

 the exotic genera, so that it appears 

 highly probable that with the pro- 

 gress of knowledge the present divi- 

 sion between social and solitary 

 wasps will prove untenable. 



Eemains of Insects referred to 

 Fig. 35.--2nisarisves2)i/or?nis. A, ma.\e-, the genera Folistes and Vespa 



B, female. Earvpt. (After Scliaum.) , ° n -, ■ . ■ 



Jiave been lound m tertiary strata 

 in various parts of Europe and in North America. 



Fam. 3. Masaridae. 



A/iterior trinjj icith two com'plete suh-vwrginal cells. Antennae 

 usually iticrassate or cluhhcd at tlie extremity. Clavs dis- 

 tinctly or ohsoletely dentate. 



This is a group of fifty or sixty species with but few genera, 



