252 W. A. LAMBORN. 



Predaceous Enemies. 



A species f dragonfly {Orthetrum cJirysostigma, Burm.) the male dull blue in colour^ 

 the female greenish blue has now been found to prey on morsitans. In February, 

 in the Lingadzi district, I saw one of these dragonflies, which had been following 

 and hovering round the party of six boys with me, suddenly swoop down and take 

 a tsetse from the back of one of the boys who was stooping at a pool to drink, its- 

 movements being extremely rapid. It settled on the grass near by and commenced 

 to devour its prey. Later on I saw a dragonfly of the same species take a morsitans 

 which had rested on a blade of grass, though again I was unable to see whether 

 the capture was effected on the wing or not ; and on the following day I saw another 

 capture a tsetse off a boy. A fact of importance in all three cases was that each 

 dragonfly accompanied our party for some little distance, obviously expecting to 

 find its prey in our vicinity. 



I have further studied these dragonflies in relation to morsitans in the Monkey 

 Bay district. They have been observed repeatedly to flit round passers-by as if in 

 search of prey, settling near by if unsuccessful. When a number of people are 

 walking in Indian file, it is quite common for the insects to make a search round 

 each, often following on a short distance behind, and I have without any difficulty 

 caught a number of specimens with their prey, in most cases tsetses, taken in the 

 neighbourhood of natives accompanying me.* 



When a dragonfly has appeared at such times as there happened to be no tsetses 

 about, further light as to the object of its presence has been obtained from time 

 to time by flicking off one's hand a tsetse with one wing clipped. So fleet are they 

 on the wing that in a number of cases the tsetse was seized before reaching the 

 ground. By this method it was ascertained that tsetse-flies, whether half starved 

 or replete with freshly ingested blood (either from a goat or a fowl) were equally 

 acceptable to the dragonfly, and after eating a replete tsetse the dragonfly has been 

 found to have the blood smeared abundantly over its face and jaws. The insect is 

 indefatigable in its work, and both sexes are to be found on the move in glades, 

 in open grass country, and on rocky barren soil far from water, whether early or late, 

 in sunshine or bad weather. The females feed and oviposit readily in captivity, the 

 eggs, which are numerous, being arranged in irregular masses. 



I have kept a look out to determine whether any other species of dragonflies 

 habitually prey on tsetses. Only one other instance occurred, and in this case the 

 insect (Crocothejnis erythraea, Brulle) handled the tsetse-fly so clumsily, gradually 

 slipping down and right round the grass stem to which it was clinging, in a vain 

 endeavour to hold its prey and support itself at the same time, as to convince me 

 that it was quite a novice with tsetses. 



Observations on the Larvae of Glossina. 



As has been already noted by previous observers, the newly born larva is covered 

 with a clear slimy secretion, and a theory has been advanced that the purpose of 

 this is to cause earth to adhere so that the pupae are less readily recognised by 



* [Dr. Laniborn has sent notes of 21 cases in wliich he saw these dragonflies take 

 tsetses on 23rd and 2-ltli Ajnil and 3rd-12th May 1915. — Ed.] 



