A year's work among gall- gnats. 87 



I have pleasure in submitting to 3^our readers my year's 

 doings among this most fascinating group of insects, and could 

 only wish that I had more to record than I have. Long years 

 are needed to elucidate fully the habits of these tiny gall-makers 

 among our Diptera. 



The first Cecid of the year is the little gnat that comes forth 

 from the last year's catkins of the birch {Cecidomyia hetulce). I 

 have reared them abundantly both this season and last. They 

 appear in March, or early in April, if the morning is sunny. 

 The contorted wings are unfolded in about twenty minutes, when 

 they begin their merry gnat-like dance. You must be an early 

 riser to notice the transformation scene. 



No sooner does the cuckoo-flower {Cardamine pratensis) show 

 its flower-buds than they are tenanted by the hirvse of Ceci- 

 domyia cardaminis, half-a-dozen or more occupying one bud, and 

 making it assume such monstrous proportions as sometimes to 

 be hardly recognised as the bud of our bonnie cuckoo-flower. 

 After years of failure I succeeded this year in raising the gnat 

 from the affected flower-heads of last year. Moisture is essential 

 for its development ; so that the flowerpot that contains the 

 larvae should stand in a saucer constantly supplied with water. 

 I know no other secrets in rearing this merry little Cecid. 

 Winnertz says that he only reared it after long years of dis- 

 appointment. As the summer comes round, another gnat-gall 

 covers the surface of the leaves of the meadowsweet {Spircea 

 ulmaria) with red and green warts. These are the home of the 

 larvsB of C. ulmarice, and an abundant progeny may be reared 

 therefrom by closely imitating Nature in her ways and means. 

 The warts of this species are rounded on the obverse, pointed on 

 the reverse, of the leaf. Each contains a single larva. July is 

 the month in which they appear in the winged state, the first 

 flight appearing about the middle of the month. I must have 

 reared fully a hundred. 



It is well to remember that the Cecids, as a group, are lovers 

 of moisture, so that it is necessary, to succeed in rearing them, 

 to sprinkle the food-plants with water each morning. Professor 

 Loew (of Posen) remarks, in his monograph on the Cecids, that 

 the larvae of these minute forms of insect-life may be resuscitated 

 even when apparently dead and shrivelled. This remark has 

 often helped me, in my investigations, in educing the perfected 

 existences. 



